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                                                                     EXHIBIT 4.1

                                 THIRD AMENDMENT

                  THIRD AMENDMENT (this "Amendment"), dated as of April 12,
2000, among INFOUSA INC., a Delaware corporation (the "Borrower"), the lenders
party to the Credit Agreement referred to below (the "Lenders"), and BANKERS
TRUST COMPANY, as Administrative Agent (the "Administrative Agent"). All
capitalized terms used herein and not otherwise defined shall have the
respective meanings provided such terms in the Credit Agreement referred to
below.

                              W I T N E S S E T H :

                  WHEREAS, the Borrower, the Lenders and the Administrative
Agent are parties to a Credit Agreement, dated as of July 23, 1999 (as amended,
modified or supplemented through, but not including, the date hereof, the
"Credit Agreement");

                  WHEREAS, the parties hereto wish to amend the Credit Agreement
as herein provided, subject to and on the terms and conditions set forth herein;

                  NOW, THEREFORE, it is agreed:

                  1. Section 2.02(i)(x) of the Credit Agreement is hereby
amended by deleting the amount of "$5,000,000" appearing therein and inserting
the amount $10,000,000" in lieu thereof:

                  2. In order to induce the Lenders to enter into this
Amendment, the Borrower hereby represents and warrants that (i) the
representations, warranties and agreements contained in Section 7 of the Credit
Agreement are true and correct in all material respects on and as of the Third
Amendment Effective Date (as defined in Section 6 of this Amendment), both
before and after giving effect to this Amendment (it being understood and agreed
that any representation or warranty which by its terms is made as of a specified
date shall be required to be true and correct in all material respects only as
of such specified date), and (ii) there exists no Default or Event of Default on
the Third Amendment Effective Date, both before and after giving effect to this
Amendment.

                  3. This Amendment is limited as specified and shall not
constitute a modification, acceptance or waiver of any other provision of the
Credit Agreement or any other Credit Document.

                  4. This Amendment may be executed in any number of
counterparts and by the different parties hereto on separate counterparts, each
of which counterparts when executed and delivered shall be an original, but all
of which shall together constitute one and the same instrument. A complete set
of counterparts shall be lodged with the Borrower and the Administrative Agent.


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                  5. THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE
PARTIES HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAW
OF THE STATE OF NEW YORK.

                  6. This Amendment shall become effective on the date (the
"Third Amendment Effective Date") when (i) the Borrower and the Required Lenders
shall have signed a counterpart hereof (whether the same or different
counterparts) and shall have delivered (including by way of facsimile
transmission) the same to the Administrative Agent at the Notice Office.

                  7. From and after the Third Amendment Effective Date, all
references in the Credit Agreement and each of the Credit Documents to the
Credit Agreement shall be deemed to be references to the Credit Agreement as
amended hereby.

                                     * * *


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                  IN WITNESS WHEREOF, each of the parties hereto has caused a
counterpart of this Amendment to be duly executed and delivered as of the date
first above written.

                                      INFOUSA INC.

                                      By:   /s/ STORMY L. DEAN
                                         ---------------------------------------
                                         Name:  Stormy L. Dean
                                         Title: Chief Financial Officer


                                      BANKERS TRUST COMPANY,
                                        Individually and as Administrative Agent

                                      By:   /s/ DAVID J. BELL
                                         ---------------------------------------
                                         Name:  David J. Bell
                                         Title: Principal


                                      US BANK NATIONAL ASSOCIATION

                                      By:   /s/ KEVIN D. MUNRO
                                         ---------------------------------------
                                         Name:  Kevin D. Munro
                                         Title: Vice President


                                      UNION BANK OF CALIFORNIA, N.A.

                                      By:   /s/ HAGOP V. JAZMADARIAN
                                         ---------------------------------------
                                         Name:  Hagop V. Jazmadarian
                                         Title: Vice President


                                     [AND OTHER PARTICIPATING LENDERS]