Document:

<PAGE>

                                                                     EXHIBIT 4.2

              FIRST AMENDMENT TO FOURTH AMENDED AND RESTATED CREDIT
                                    AGREEMENT

         This First Amendment to Fourth Amended and Restated Credit Agreement
(this "Amendment") is made as of this 13th day of March, 2003 by and Developers
Diversified Realty Corporation, a corporation organized under the laws of the
State of Ohio (the "Borrower"), Bank One, NA, having its principal office in
Chicago, Illinois and the several banks, financial institutions and other
entities from time to time parties to this Agreement (the "Lenders"), and Bank
One, NA, not individually, but as "Administrative Agent".

                                    RECITALS

         A.       Borrower, Administrative Agent, and the Lenders are parties to
a Fourth Amended and Restated Credit Agreement dated as of May 29, 2002 (the
"Credit Agreement"). All capitalized terms used in this Amendment and not
otherwise defined herein shall have the meanings described as such terms in the
Credit Agreement.

         B.       Pursuant to the terms of the Credit Agreement, the Lenders
made available a credit facility with a potential Aggregate Commitment of
$650,000,000.

         C.       Borrower, JDN Realty Corporation, a Maryland corporation ("JDN
Realty"), and DDR Transitory Sub, Inc., a Maryland corporation, have entered
into an Agreement and Plan of Merger dated as of October 4, 2002 (the "Merger
Agreement"), pursuant to which JDN Realty will become a Wholly-Owned Subsidiary
of Borrower through the consummation of various merger transactions as more
particularly described in the Merger Agreement (collectively, such transactions
are referred to as the "Merger").

         D.       Borrower has requested a change in certain terms contained in
the Credit Agreement in order to facilitate the Merger.

         NOW, THEREFORE, in consideration of the foregoing recitals and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto agree as follows:

                                   AMENDMENTS

         1.       The foregoing recitals to this Amendment are incorporated into
and made part of this Amendment.

         2.       The definition of "Value of Unencumbered Assets" in Article 1
of the Credit Agreement is hereby amended by changing clause (B) to read as
follows:

                  "(B) for each Pre-Leased Project Under Construction, 100
                  percent of the then current book value, as determined in
                  accordance with GAAP, of such Pre-Leased Project Under
                  Construction, provided that the aggregate amount added to
                  value under this clause (B) shall not exceed 10 percent of the
                  total Value of Unencumbered Assets."
<PAGE>

         3.       Section 6.19 of the Credit Agreement is hereby amended and
restated as follows:

                  Variable Interest Indebtedness. The Borrower and its
                  Subsidiaries shall not at any time permit the outstanding
                  principal balance of Indebtedness which bears interest at an
                  interest rate that is not fixed through the maturity date of
                  such Indebtedness to exceed $1,100,000,000, unless all of such
                  Indebtedness in excess of $1,100,000,000 is subject to a Rate
                  Management Transaction approved by the Administrative Agent
                  that effectively converts the interest rate on such excess to
                  a fixed rate.

         4.       Section 6.21 (i) of the Credit Agreement is hereby amended and
restated as follows:

                  Consolidated Outstanding Indebtedness to exceed (A)
                  fifty-eight percent (58%) of Consolidated Market Value as of
                  any date through and including December 30, 2003, and (B)
                  fifty-five percent (55%) of Consolidated Market Value as of
                  any date thereafter;

         5.       Borrower hereby represents and warrants that:

                  (a)      no Default or Unmatured Default exists under the Loan
                           Documents;

                  (b)      the Loan Documents are in full force and effect and
                           Borrower has no defenses or offsets to, or claims or
                           counterclaims relating to, its obligations under the
                           Loan Documents;

                  (c)      there has been no material adverse change in the
                           financial condition of Borrower as shown in its
                           September 30, 2002 financial statements;

                  (d)      Borrower has full corporate power and authority to
                           execute this Amendment and no consents are required
                           for such execution other than any consents which have
                           already been obtained; and

                  (e)      all representations and warranties contained in
                           Article 5 of the Credit Agreement are true and
                           correct as of the date hereof and all references
                           therein to "the date of this Agreement" shall refer
                           to "the date of this Amendment."

         6.       Except as specifically modified hereby, the Credit Agreement
is and remains unmodified and in full force and effect and is hereby ratified
and confirmed. All references in the Loan Documents to the "Credit Agreement"
henceforth shall be deemed to refer to the Credit Agreement as amended by this
Amendment.

         7.       This Amendment may be executed in any number of counterparts,
all of which taken together shall constitute one agreement, and any of the
parties hereto may execute this Amendment by signing any such counterpart. This
Amendment shall be construed in accordance with the internal laws (and not the
law of conflicts) of the State of Illinois, but giving effect to federal laws
applicable to national banks.

                                       -2-

<PAGE>

         8.       This Amendment shall become effective when (i) it has been
executed by Borrower, Administrative Agent, and the Required Lenders; and (ii)
the Merger has been completed.

                                       -3-

<PAGE>

                  IN WITNESS WHEREOF, the Borrower, the Lenders and the
Administrative Agent have executed this Amendment as of the date first above
written.

                                DEVELOPERS DIVERSIFIED REALTY
                                CORPORATION

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                3300 Enterprise Parkway
                                Beachwood, Ohio  44122
                                Phone:  216/755-5506
                                Facsimile:  216/755-1506
                                Attention:  Scott A. Wolstein

                                       S-1

<PAGE>

                                BANK ONE, NA,
                                Individually and as Administrative Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                1 Bank One Plaza, IL 1-0315
                                Chicago, Illinois  60670
                                Phone:  312/732-4000
                                Facsimile:  312/732-5939
                                Attention:  Corporate Real Estate

                                       S-2

<PAGE>

                                BANK OF AMERICA, N.A.,
                                Individually and as Syndication Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                231 South LaSalle Street
                                Chicago, IL 60697
                                Phone:  312/828-5215
                                Facsimile:  312/828-4970
                                Attention:  Ms. Cheryl Gray

                                       S-3

<PAGE>

                                COMMERZBANK AG,
                                Individually and as Documentation Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                and by:

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                2 World Financial Center
                                New York, NY 10281-1050
                                Phone:  212/400/7569
                                Facsimile:  212/266-7565
                                Attention:  Mr. Douglas Traynor

                                       S-4

<PAGE>

                                DEUTSCHE BANK SECURITIES, INC.
                                Individually and as Documentation Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                31 West 52nd Street
                                New York, NY 10019
                                Phone:  646/324-2118
                                Facsimile:  646/324-7450
                                Attention:  Mr. Geoff Bedrosian

                                       S-5

<PAGE>

                                FLEET BANK,
                                Individually and as Documentation Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                100 Federal Street
                                Boston, MA 02110
                                Phone:  617/434-6322
                                Facsimile:  617/434-6384
                                Attention:  Mr. James Keough

                                       S-6

<PAGE>

                                WELLS FARGO BANK, N.A.,
                                Real Estate Finance Group,
                                Individually and as Documentation Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                225 West Wacker
                                Suite 2550
                                Chicago, IL 60606
                                Phone:  312/269-4818
                                Facsimile:  312/782-0969
                                Attention:  Mr. Scott Solis

                                       S-7

<PAGE>

                                WACHOVIA BANK, NA.,
                                Individually and as Managing Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                Mail Code GA-31281, 28th Floor
                                191 Peachtree St., N.E.
                                Atlanta, GA 30303
                                Phone:  404/332-5080
                                Facsimile:  404/332-4066
                                Attention:  Mr. John Blackwelder

                                       S-8

<PAGE>

                                FIRSTAR BANK, N.A.,
                                Individually and as Co-Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                1350 Euclid Avenue
                                Cleveland, OH 44115
                                Phone:  216/623-5984
                                Facsimile:  216/241-0164
                                Attention:  Mr. Samuel Russo

                                       S-9

<PAGE>

                                ING CAPITAL LLC,
                                Individually and as Co-Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                1325 Avenue of the Americas
                                New York, NY 10019
                                Phone:  646/424-6209
                                Facsimile:  212/424/6210
                                Attention:  Mr. David Lattimer

                                      S-10

<PAGE>

                                JP MORGAN CHASE,
                                Individually and as Co-Agent

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                270 Park Avenue
                                New York, NY 10017
                                Phone:  212/270-9562
                                Facsimile:  212/270-3515
                                Attention:  Mr. John F. Mix

                                      S-11

<PAGE>

                                AM SOUTH BANK

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                1900 Fifth Avenue North
                                Birmingham, AL 35203
                                Phone:  205/326-4071
                                Facsimile:  205/326-4075
                                Attention:  Mr. Robert Blair

                                      S-12

<PAGE>

                                THE HUNTINGTON NATIONAL BANK

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                917 Euclid Avenue
                                Cleveland, OH 44115
                                Phone:  216/515-0683
                                Facsimile:  216/515-6369
                                Attention:  Mr. Richard Goss

                                      S-13

<PAGE>

                                LASALLE BANK, N.A.

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                135 South LaSalle Street
                                Suite 1225
                                Chicago, IL 60603
                                Phone:  312/904-1273
                                Facsimile:  312/904-6691
                                Attention:  Mr. Eric Ogden

                                      S-14

<PAGE>

                                LEHMAN COMMERCIAL PAPER INC.

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                399 Park Ave., 8th Floor
                                New York, NY 10022
                                Phone:  212/526-5153
                                Facsimile:  646-758-4672
                                Attention:  Mr. Tom Buffa

                                      S-15

<PAGE>

                                PNC BANK, NATIONAL ASSOCIATION

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                One PNC Plaza
                                249 Fifth Avenue
                                Pittsburgh, PA 15222
                                Phone:  412/768-2376
                                Facsimile:  412/762-6500
                                Attention:  Mr. Andrew White

                                      S-16

<PAGE>

                                CITICORP REAL ESTATE, INC.

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                390 Greenwich Street
                                New York, NY 10013
                                Phone:  212/723-6789
                                Facsimile:  212/723-8547
                                Attention:  Mr. Michael Psyllos

                                      S-17

<PAGE>

                                ERSTE BANK

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                280 Park Avenue
                                West Building
                                New York, NY 10017
                                Phone:  212/984-5638
                                Facsimile:  212/984-5627
                                Attention:  Mr. Gregory Aptman

                                      S-18

<PAGE>

                                MELLON BANK, N.A.

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                Suite 5325
                                One Mellon Center
                                Pittsburgh, PA 15258-0001
                                Phone:  412/234-9625
                                Facsimile:  412/234-8657
                                Attention:  Mr. Thomas Greulich

                                      S-19

<PAGE>

                                THE NORTHERN TRUST COMPANY

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                50 South LaSalle Street
                                Chicago, IL 60675
                                Phone:  312/444-3380
                                Facsimile:  312/444-7028
                                Attention:  Mr. Robert Wiarda

                                      S-20

<PAGE>

                                SOUTHTRUST BANK

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                420 North 20th Street
                                Birmingham, AL 35203
                                Phone:  205/254-4438
                                Facsimile:  205/254-8270
                                Attention:  Mr. Ronnie Brantley

                                      S-21

<PAGE>

                                ALLIED IRISH BANKS, P.L.C.
                                New York Branch

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                405 Park Avenue
                                New York, NY 10022
                                Phone:  212/515-6847
                                Facsimile:  212/339-8325
                                Attention:  Mr. Anthony O'Reilly
                                            Ms. Hillary Patterson

                                      S-22

<PAGE>

                                CHANG HWA BANK

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                685 3rd Avenue, 29th Floor
                                New York, NY 10017
                                Phone:  212/651-9770 ext. 29
                                Facsimile:  212/651-9785
                                Attention:  Vivian Chen

                                      S-23

<PAGE>

                                COMPASS BANK

                                By:_________________________________________
                                Print Name:_________________________________
                                Title:______________________________________

                                15 South 20th Street
                                15th Floor
                                Birmingham, AL 35233
                                Phone:  205/297-3851
                                Facsimile:  205/297-7994
                                Attention:  Johanna Paley

                                      S-24<PAGE>

Exhibit 10(l) Second Amendment to Credit Agreement

                      SECOND AMENDMENT TO CREDIT AGREEMENT

                  THIS SECOND AMENDMENT TO CREDIT AGREEMENT, dated as of March
28, 2003 (this "Amendment"), is among KEITHLEY INSTRUMENTS, INC., an Ohio
corporation (the "Company"), Subsidiary Borrowers (referred to below and
collectively with the Company, the "Borrowers"), the Lender (as referred to
below) and BANK ONE, NA, a national banking association, having its principal
office in Columbus, Ohio, as Agent for the Lender (in such capacity the
"Agent").

                                    RECITALS

                  A.       The Company, certain Subsidiary Borrowers party
thereto, the Lender party thereto and Agent are parties to a Credit Agreement,
dated as of March 30, 2001, as amended by a First Amendment to Credit Agreement
dated as of August 1, 2002 (as now and hereafter amended, the "Credit
Agreement"), pursuant to which the Lender agreed, subject to the terms and
conditions thereof, to extend credit to the Borrowers.

                  B.       The Borrowers desire to amend the Credit Agreement
and the Agent and the Lender are willing to do so strictly in accordance with
the terms hereof.

                                      TERMS

                  In consideration of the premises and of the mutual agreements
herein contained, the parties agree as follows:

                                   ARTICLE 1.
                                   AMENDMENTS

                  Upon fulfillment of the conditions set forth in Article 3
hereof, the Credit Agreement shall be amended as follows:

         1.1      Article I shall be amended by deleting the following
definitions in their entirety:

                  "Consolidated Current Assets", "Consolidated Current
         Liabilities", "EBIDA Plus Non-Recurring Expense", "Pricing Schedule"
         and "Working Capital".

         1.2      Article I shall be amended by adding the following definitions
in appropriate alphabetical order.

                  "Cash Equivalent Investments" means (i) short-term obligations
         of, or fully guaranteed by, the United States of America, (ii)
         commercial paper rated A-1 or better by S&P or P-1 or better by
         Moody's, (iii) demand deposit accounts maintained in the ordinary
         course of business, (iv) certificates of deposit issued by and time
         deposits with commercial banks (whether domestic or foreign) having
         capital and surplus in excess of $100,000,000 and (v) marketable
         securities, mutual funds and other marketable investments acceptable to
         the Agent.

<PAGE>

                  "Consolidated Liquid Assets" means the aggregate amount of all
         cash and Cash Equivalent Investments maintained by the Company and its
         Subsidiaries on a consolidated basis.

                  "Consolidated Tangible Net Worth" means at any time (i) the
         consolidated stockholders' equity of the Company and its Subsidiaries
         minus, (ii) to the extent included in determining the amount under the
         foregoing clause (i), the net book value of goodwill, cost in excess of
         fair value of net assets acquired, patents, trademarks, tradenames and
         copyrights, treasury stock and all other assets which are deemed
         intangible assets under Agreement Accounting Principles, all calculated
         on a consolidated basis.

                  "EBDA minus Distributions" means, for any period, (a)
         Consolidated Net Income for such period plus, to the extent deducted
         from revenues in determining Consolidated Net Income, (i) depreciation
         expense, and (ii) amortization expense, minus (b) the aggregate amount
         of dividends or other distributions paid to shareholders of the Company
         during such period, all calculated for the Company and its Subsidiaries
         on a consolidated basis.

         1.3      The definition of "Applicable Margin" in Article I shall be
amended and restated in its entirety to read as follows:

                  "Applicable Margin" means (i) with respect to Floating Rate
         Loans, 0%; (ii) with respect to Eurocurrency Loans denominated in
         Dollars, 1.00%; and (iii) with respect to Eurocurrency Loans
         denominated in any Agreed Currency other than Dollars, the margin
         quoted by the Agent and agreed to by the Company at the time any such
         Eurocurrency Loan is requested.

         1.4      Section 2.1 shall be amended by adding a new clause (iii) to
the proviso clause which begins in line 4 to read as follows:

                  "and (iii) the aggregate amount of the Aggregate Outstanding
                  Credit Exposure of Subsidiary Borrowers shall not exceed the
                  Dollar Amount of $5,000,000."

         1.5      Section 2.5 shall be amended by deleting the reference in line
three therein to "the Applicable Fee Rate" and inserting "one-quarter of one
percent" in place thereof.

         1.6      Section 6.16 shall be amended and restated in its entirety to
read as follows:

                  6.16.  Financial Covenants

                           6.16.1.  Funded Debt to Tangible Net Worth.  The
         Company will not permit the ratio of Consolidated Funded Debt to
         Consolidated Tangible Net Worth, determined as of the end of each of
         its fiscal quarters to be greater than 0.15 to 1.0.

                           6.16.2.  EBDA minus Distributions and Liquid Assets.
         In the event the amount of EBDA minus Distributions is a negative
         number, the Company will not permit (i) EBDA minus Distributions,
         calculated as of the last day of each fiscal quarter for the four
         consecutive fiscal quarters then ending, to exceed 10% of Consolidated
         Liquid Assets, and (ii) EBDA minus Distributions, calculated as of the
         last day of each fiscal quarter for the fiscal quarter then ending and
         annualized, to exceed 15% of Consolidated Liquid Assets. In the event
         the amount of EBDA minus Distributions is a positive number, this
         covenant will be inapplicable.

                                       -2-
<PAGE>

         1.7      The Pricing Schedule to the Credit Agreement shall be deleted
in its entirety.

         1.8      Schedule 1.1 to the Credit Agreement shall be replaced with
the form of Schedule 1.1 attached to this Amendment.

                                   ARTICLE 2.
                                 REPRESENTATIONS

                  Each Borrower represents and warrants to the Agent and the
Lender that:

         2.1      The execution, delivery and performance of this Amendment is
within its powers, has been duly authorized and is not in contravention with any
law, of the terms of its Articles of Incorporation or By-laws, or any
undertaking to which it is a party or by which it is bound.

         2.2      This Amendment is the legal, valid and binding obligation of
the Borrower enforceable against it in accordance with the terms hereof.

         2.3      After giving effect to the amendments herein contained, the
representations and warranties contained in Article V of the Credit Agreement
are true on and as of March 28, 2003 with the same force and effect as if made
on and as of March 28, 2003.

         2.4      No Default or Unmatured Default exists or has occurred and is
continuing on the date hereof.

                                   ARTICLE 3.
                           CONDITIONS OF EFFECTIVENESS

                  This Amendment shall not become effective until each of the
following has been satisfied:

         3.1      This Amendment shall be signed by each Borrower (including the
New Subsidiary Borrowers (as defined below)), the Agent and the Lender.

         3.2      Each of the Subsidiary Borrowers set forth on Schedule 1.1
attached hereto other than Keithley Instruments GmbH (the "New Subsidiary
Borrowers") shall execute and deliver a Joinder Agreement and such other
opinions of counsel and other documents with respect to the New Subsidiary
Borrowers as reasonably required by the Agent and the Lenders pursuant to
Section 8.2.2 of the Credit Agreement.

         3.3      The Company shall have paid an amendment fee in the amount of
$5,000.

                                   ARTICLE 4.
                                 MISCELLANEOUS.

         4.1      References in the Credit Agreement or in any note,
certificate, instrument or other document to the "Credit Agreement" shall be
deemed to be references to the Credit Agreement as amended hereby and as further
amended from time to time.

                                       -3-
<PAGE>

         4.2      The Company agrees to pay and to save the Agent harmless for
the payment of all costs and expenses arising in connection with this Amendment,
including the reasonable fees of counsel to the Agent in connection with
preparing this Amendment and the related documents.

         4.3      Each Borrower acknowledges and agrees that the Agent and the
Lender have fully performed all of their obligations under all documents
executed in connection with the Credit Agreement and all actions taken by the
Agent and the Lender are reasonable and appropriate under the circumstances and
within their rights under the Credit Agreement and all other documents executed
in connection therewith and otherwise available. Each Borrower represents and
warrants that it is not aware of any claims or causes of action against the
Agent or any Lender, any participant lender or any of their successors or
assigns.

         4.4      Except as expressly amended hereby, each Borrower agrees that
the Credit Agreement and all other Loan Documents are ratified and confirmed and
shall remain in full force and effect and that it has no set off, counterclaim
or defense with respect to any of the foregoing. Terms used but not defined
herein shall have the respective meanings ascribed thereto in the Credit
Agreement.

         4.5      This Amendment may be signed upon any number of counterparts
with the same effect as if the signatures thereto and hereto were upon the same
instrument.

                  IN WITNESS WHEREOF, the parties signing this Amendment have
caused this Amendment to be executed and delivered as of March 28, 2003.

                                        KEITHLEY INSTRUMENTS, INC.

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its: VP & CFO
                                                -----------------------

                                        KEITHLEY INSTRUMENTS GmbH

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its: Managing Director
                                                -----------------------

                                        KEITHLEY INSTRUMENTS SARL

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its: Managing Director
                                                -----------------------

                                        KEITHLEY INSTRUMENTS LTD.

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its: Managing Director
                                                -----------------------

                                       -4-
<PAGE>

                                        KEITHLEY INSTRUMENTS SRL

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its: Managing Director
                                                -----------------------

                                        KEITHLEY INSTRUMENTS BV

                                        By: /s/ Joseph P. Keithley
                                            ---------------------------

                                           Its: Chairman
                                                -----------------------

                                        KEITHLEY INSTRUMENTS SA

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its: Managing Director
                                                -----------------------

                                        KEITHLEY INSTRUMENTS KK

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its Managing Director
                                               ------------------------

                                        KEITHLEY INTERNATIONAL
                                        INVESTMENT CORP.

                                        By: /s/ Mark J. Plush
                                            ---------------------------

                                           Its: Managing Director
                                                -----------------------

                                        BANK ONE, NA, as Agent,
                                        LC Issuer and Lender

                                        By: /s/ Shawn G. Konya
                                            ---------------------------

                                           Its: Officer
                                                -----------------------

                                       -5-
<PAGE>

                                  SCHEDULE 1.1

                              SUBSIDIARY BORROWERS

Keithley Instruments GmbH, an entity organized under the laws of Germany

Keithley Instruments SARL, an entity organized under the laws of France

Keithley Instruments Ltd., an entity organized under the laws of Great Britain

Keithley Instruments SRL, an entity organized under the laws of Italy

Keithley Instruments BV, an entity organized under the laws of Netherlands

Keithley Instruments SA, an entity organized under the laws of Switzerland

Keithley Instruments KK, an entity organized under the laws of Japan

Keithley International Investment Corp., an entity organized under the laws of
Delaware.

                                      -6-

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