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                                                                 Exhibit 3.150


                        WRITTEN AGREEMENT OF SHAREHOLDERS

                                       OF

                         CAMBRIDGE RESEARCH GROUP, LTD.

      Edward T. Gardner, III and Catherine H. White being the sole shareholders
of Cambridge Research Group, Ltd. (the "Corporation"), pursuant to the
provisions of P.31-1-73 of the West Virginia Code, 1981, as amended, hereby
dispenses with a meeting and vote of the shareholders of the Corporation, and
agrees in writing to the following corporate action being taken:

      RESOLVED: That the attached By Laws are adopted as the By Laws for the
government of the Corporation.

      RESOLVED: That the following persons are elected directors of the
Corporation:

                             EDWARD T. GARDNER, III
                               CATHERINE H. WHITE

      Dated this 31st day of August, 1981.


                                               /s/ Edward T. Gardner, III    
                                               ----------------------------- 
                                               EDWARD T. GARDNER, III        
                                                                             
                                               /s/ Catherine H. White        
                                               ----------------------------- 
                                               CATHERINE H. WHITE            
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                         CAMBRIDGE RESEARCH GROUP, LTD.

                                     BYLAWS

                                    ARTICLE I

                                     OFFICES

      Section 1. The principal office of the corporation shall be located at P.
0. Box 389, 808 Union Building, Charleston, West Virginia 25322, provided that
the Board of Directors shall have power to change the location of the principal
office at its discretion.

      Section 2. The corporation may also have offices and keep its books at
such other place or places within the State of West Virginia as the Board of
Directors may from time to time appoint, or as the business of the corporation
may require.

                                   ARTICLE II

                        Shareholders and shares of stock

      Section 1. Annual Meetings. The annual meeting of the shareholders shall
be held on the first Monday in January of each calendar year or on such other
date in the month of January as may be designated in the notice and call of such
meeting, at the principal office of the corporation, or at such other place
either within or without the State of West Virginia as the Board of Directors
shall, from time to time, determine, and the place and the hour at which such
meeting shall be held shall be stated in the notice and call of such meeting. At
such meeting, the Board of Directors shall be elected and such other business
shall be transacted as is usual at the annual meeting of a corporation. Such
Meeting may adjourn to a later date, and no notice of such adjourned meeting
shall be necessary. If such meeting be not held as herein prescribed, the
election of directors to succeed those whose terms expire may be held at any
meeting thereafter called pursuant to these Bylaws.
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      Section 2. Special Meetings. Special meetings of the shareholders may be
held at such places within the State of West Virginia as may be designated in
the notice and call of such meeting, or if no place be specified, then at the
principal office of the corporation; provided, however, that when called by the
Board of Directors any special meeting of the shareholders may be held either
within or without the State of West Virginia at such place as may be designated
in the notice and call of such meeting. Special meetings of the shareholders may
be called by the Board of Directors, the President, any Vice President, the
Secretary, or any number of shareholders owning in the aggregate at least one
tenth of the number of shares outstanding. The notice of special meetings shall
state the business to be transacted, and no business other than that included in
the notice or incidental thereto shall be transacted at such meeting. Special
meetings may adjourn to a later date, and no notice of such adjourned meeting
shall be necessary.

      Section 3. Notice of Meetings. Notice of annual and special meetings shall
be given by mailing to each shareholder a written notice thereof specifying the
time and place of such meeting, and, in the case of special meetings, the
business to be transacted, as hereinbefore set forth, such notice to be mailed
to the last addresses of the shareholders as they respectively appear upon the
books of the corporation, and in the case of annual meetings not less than ten
(10) days, and in the case of special meetings not less than five (5) days,
before the date of such meeting and the mailing of such notice shall be
sufficient and no publication or further notice shall be sufficient and no
publication or further notice shall be necessary. Such notice may be signed by
the President or a Vice President or the Secretary or an Assistant Secretary.

      Section 4. Waiver of Notice. Notice of the time, place or purpose of any
meeting of shareholders, whether required by the provisions of the corporation
laws of the State of West Virginia or by these Bylaws, shall be dispensed with
if every shareholder shall attend such meeting either in person or by proxy, or
if every absent shareholder shall, in writing filed with the records of the
meeting either before or after the holding thereof, waive such notice.

      Section 5. Action by Unanimous Consent. Whenever the vote of shareholders
at a meeting thereof is required or permitted to be taken in connection with any
corporate action, the meeting and vote of such shareholders may be dispensed
with if all of the shareholders who would have been entitled to vote upon the
action if such meeting were held, shall agree in writing to such corporation
action being taken, and such agreement shall have like effect and validity as
though the action were duly taken by the unanimous action of all shareholders
entitled to vote at a meeting of such shareholders duly called and legally held.
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      Section 6. Quorum. A quorum of the shareholders shall consist of at least
a majority of all of the shares of stock entitled to vote. Any number less than
a quorum present may adjourn any shareholders' meeting until a quorum is
present, and no notice as to such adjourned meeting shall be necessary.

      Section 7. Voting Rights. In all elections of directors of the
corporation, each shareholder shall have the right to cast one vote for each
share of stock owned by him and entitled to a vote, and he may cast the same in
person or by proxy for as many persons as there are directors to be elected, or
he may cumulate such votes and give one candidate as many votes as the number of
directors to be elected multiplied by the number of his shares of stock shall
equal; or he may distribute them on the same principle among as many candidates
and in such manner as he shall desire, and the directors shall not be elected in
any other manner; and on any other question to be determined by a vote of shares
at any meeting of shareholders, each shareholder shall be entitled to one vote
for each share of stock owned by him and entitled to a vote, and he may exercise
this right in person or by proxy; provided, however, no voting rights shall
attach to any fractional part of a share of stock, and no person shall vote on
any proxy after three (3) years from the date thereof, unless the proxy
specifically confers the right to vote for a longer period and then only within
the period specified.

      Section 8. Organization of Shareholders' Meeting. The President of the
corporation, or, in his absence, a Vice President shall call the meetings of the
shareholders to order and shall act as Chairman of such meetings, and the
Secretary or an Assistant Secretary of the corporation shall act as Secretary of
such meetings. In the absence of such officers, or any one of them, the meeting
shall designate the Chairman and/or Secretary, as the case may be.

      Section 9. Order of Business. No formal order of business need be followed
in any meeting, regular or special, of the shareholders.

      Section 10. Certificates for Shares of Stock. Every holder of shares of
stock in this corporation, when the same shall be fully paid for, shall be
entitled to have a certificate signed by, or in the name of the corporation by,
the President or a Vice President and the Secretary or an Assistant Treasurer,
of this corporation, certifying the number of shares owned by him in this
corporation.

      Section 11. Lost or Destroyed Stock Certificates. A certificate of stock
may be issued in lieu of the certificate lost or destroyed upon compliance with
the following terms and conditions by the person who appears by the books of the
corporation to be the owner of the lost or destroyed certificate, that is to
say: (a) Such apparent owner shall file with the officers of the corporation,
first, an affidavit setting forth the time, place and circumstances of the loss
to the best
<PAGE>

of his knowledge, and belief; second, proof of his having advertised the loss in
a newspaper of general circulation published near the principal office of the
corporation once a week for two weeks; and (b) he shall execute and deliver to
the corporation a bond with good security, in a penalty of at least the value of
the shares of stock represented by the lost or destroyed certificate,
conditioned to indemnify the corporation and all persons whose rights may be
affected by the issuance of the new certificate against any loss in consequence
of the new certificate being issued; provided, however, that a new certificate
may be issued in lieu of the one lost in the discretion of the Board of
Directors, without requiring the publication of the above notice or the giving
of a bond.

      Section 12. Ownership of Capital Stock. The person in whose name shares of
stock stand on the books of the corporation shall be deemed the owner thereof so
far as the corporation is concerned. The personal representatives of a deceased
stockholder shall be entitled to vote the shares of stock of his decedent
without having any such shares transferred to him. No voting right shall be
given to any stock while owned by the corporation nor shall any stock so held be
entitled to any dividend.

      Section 13. Stock Transfer Books. Stock transfer books shall be kept by
the Secretary of the corporation, in which the shares shall be transferred under
such regulations as may be prescribed by the Board of Directors.

      Section 14. Restrictions on Transfer, Pledge or Sale of Stock. The rights
to subscribe for, and to transfer, pledge or sell, shares of stock of this
corporation may be made subject to such conditions and restrictions as are
provided for in any written agreement among and between the stockholders and
this corporation that may be authorized and approved by the Board of Directors.

      Section 15. Closing of Stock Books. The Board of Directors are authorized
to fix the time, not exceeding forty (40) days preceding the date of any meeting
of the shareholders or any dividend payment date, or any date for the allotment
of rights, during which the books of the corporation shall be closed against the
transfer of stock, or in lieu of providing for the closing of the books against
transfer of stock, the Board of Directors are authorized to fix a date, not
exceeding forty (40) days preceding the date of any meeting of the shareholders
or any dividend payment date, or any date for allotment of rights, as a record
date for the determination of the shareholders entitled to notice of, or to vote
at, such meeting and/or entitled to receive such dividend payments or rights, as
the case may be, and only shareholders of record on such date shall be entitled
to notice of and/or to vote at such meeting or to receive such dividend payments
or rights.

                                   ARTICLE III

                                    Director

      Section 1. Board of Directors. The business and affairs of
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the corporation shall be managed by a Board of Directors. Directors need not be
residents of the State of West Virginia or shareholders in the corporation.

      Section 2. Election of Directors. The number of directors shall be at
least two (2) provided that the number may be increased or decreased from time
to time by an amendment to these Bylaws, but no increase shall have the effect
of shortening the term of any incumbent director. The directors shall be elected
at each annual meeting of the shareholders, or any adjournment thereof, to serve
until the next annual meeting of the shareholders or until their offices shall
be declared vacant, or until their successors are elected and qualified.

      Section 3. Vacancies. Any vacancy occurring in the Board of Directors may
be filled by the affirmative vote of the remaining directors, though less than a
quorum of the Board. Any directorship to be filled by reason of an increase in
the number of directors shall be filled by election at an annual meeting or at a
special meeting of shareholders called for that purpose. A director elected to
fill a vacancy shall be elected for the unexpired term of his predecessor in
office.

      Section 4. Quorum of Directors. A majority of the Board of Directors shall
constitute a quorum for the transaction of business. The act of the majority of
the directors present at a meeting at which a quorum is present shall be the act
of the Board of Directors.

      Section 5. Annual Meeting of Directors. Within thirty (30) days after each
annual meeting of shareholders, the Board of Directors elected at such meeting
shall hold an annual meeting at which they shall elect officers and transact
such other business as may come before the meeting.

      Section 6. Regular Meetings of Directors. A regular meeting of the Board
of Directors may be held at such time as shall be determined from time to time
by resolution of the Board of Directors.

      Section 7. Special Meetings of Directors. The Secretary shall call a
special meeting of the Board of Directors whenever requested to do so by the
President or by two (2) directors. Such special meeting shall be held at the
time specified in the notice of meeting.

      Section 8. Place of Directors' Meeting. All meetings of the Board of
Directors (annual, regular or special) shall be held either at the principal
office of the corporation or at such other place, either within or without the
State of West Virginia, as shall be specified in the notice of meeting.

      Section 9. Notice of Directors' Meetings. All meetings of the Board of
Directors (annual, regular or special) shall be held upon not less than three
(3) days written notice stating the date, place and hour of meeting delivered to
each director either personally or by mail at the direction of the President or
the Secretary of the officer or person calling the meeting.
<PAGE>

      Section 10. Waiver of Notice. Notice of the time, place or purpose of any
meeting of directors, whether required by the provisions of the corporation laws
of the State of West Virginia or by these Bylaws, shall be dispensed with if
every director shall attend such meeting in person, or if every absent director
shall, in writing filed with the records of the meeting either before or after
the holding thereof, waive such notice.

      Section 11. Action by Unanimous Consent. Whenever the vote of directors at
a meeting thereof is required or permitted to be taken in connection with any
corporate action, the meeting and vote of such directors may be dispensed with
if all the directors shall agree in writing to such corporate action being
taken, and such agreement shall have like effect and validity as though the
action were duly taken by the unanimous action of all directors at a meeting of
such directors duly called and legally held.

      Section 12. Specification of Purpose of Meeting Not Required. Neither the
business to be transacted at, nor the purpose of, any annual, regular or special
meeting of the Board of Directors need be specified in the notice or waiver of
notice of such meeting.

      Section 13. Order of Business. No formal order of business need be
followed in any meeting of the directors, either regular or special.

      Section 14. Committees. The Board of Directors may, by resolution or
resolutions passed by a majority of the whole Board, designate one or more
committees, each committee to consist of two or more of the directors of the
corporation, which, to the extent provided in such resolution or resolutions,
shall have and may exercise the powers of the Board of Directors in the
management of the business and affairs of the corporation, and may have power to
authorize the seal of the corporation to be affixed to all papers which may
require it. Such committee or committees shall have such name or names as may be
determined from time to time by resolution adopted by the Board of Directors.

      Section 15. Election of Officers. The directors shall elect the President,
one or more Vice Presidents, the Treasurer and Secretary of the corporation, and
may elect all other officers and agents, or, as to the latter, may delegate
their election to an officer and/or officers of the corporation. In addition to
the foregoing officers, the Board of Directors may designate such other officers
or officials as from time to time may be deemed advisable, and may prescribe
their duties. The directors shall have the power to fix the salaries of all
officers, agents and employees of the corporation, but in the absence of action
by the directors, such power shall be vested in the President, except as to his
own salary and that of any Vice President.

      Section 16. Compensation. Directors, as such, shall not receive any stated
salary for their services, but by resolution of the Board of Directors a fixed
sum and expenses of attendance, if any, may
<PAGE>

be allowed for attendance at each annual, regular or special meeting of the
Board, provided, that nothing herein contained shall be construed to preclude
any director from serving the corporation in any other capacity and receiving
compensation therefor.

                                   ARTICLE IV

                               Officers and Agents

      Section 1. Officers. Officers of the corporation shall be a
President/Treasurer, and a Secretary/Vice President each of whom shall be chosen
by the Board of Directors, and, if from time to time designated and chosen by
the Board of Directors, an Assistant Secretary and an Assistant Treasurer. None
of the officers of the corporation need be a shareholder or director of the
corporation. Any two of the above named officers, except those of the President
and Secretary or Assistant Secretary, may be held by the same person, but no
officer shall execute, acknowledge, or verify any instrument in more than one
capacity, if such instrument is required by law or by these Bylaws to be
executed, acknowledged, verified or countersigned by any two or more officers.
The foregoing officers shall hold office until the next regular annual meeting
of the Board of Directors, held after the annual meeting of the shareholders,
and until their successors are elected and qualified. Any duty to be performed
by an officer of the corporation may be performed by his duly authorized
assistant officer.

      Section 2. Removal of Officers. Any and all officers of the corporation
may he removed at any time and their successors elected by a majority vote of
the Board of Directors at any regular or special meeting of the directors.

      Section 3. Agents and Employees. All agents and employees of the
corporation may be appointed and their salaries fixed by the Board of Directors,
by the President, and except as to any Vice President, the Secretary, and
Assistant Secretary, the Treasurer and the Assistant Treasurer, they shall hold
office during the will and pleasure of the President, subject to action by the
Board of Directors, and may be removed at any time by the President, subject to
action by the Board of Directors. If such agents and employees are appointed by
the directors, they (except the above specified officers) may nevertheless be
removed by the President, unless he be expressly forbidden so to do by the
directors.

      Section 4. Powers and Duties of the President. The President shall preside
at all meetings of the shareholders and the Board of Directors. Subject to the
control of the Board of Directors, he shall have general charge of the business
of the corporation; he shall keep the Board of Directors fully informed of the
business of the corporation; he may sign and execute all authorized bonds,
contracts or other obligations in the name of, and on behalf of the corporation;
and, with the
<PAGE>

Secretary or an Assistant Secretary, or the Treasurer or an Assistant Treasurer,
he shall sign all certificates of stock; and, without further authorization than
these presents, he may sign all checks and/or drafts upon funds of the
corporation in its name and on its behalf, and any bank or depository in which
funds of the corporation shall be deposited shall be fully and conclusively
protected in honoring any checks and/or drafts on behalf of the corporation
signed by the President. Subject to the action of the Board of Directors, he
shall have the power to fix the salaries of all officers, agents and employees
of the corporation, except the President and Vice Presidents, and shall have the
power to employ and discharge all agents and employees of the corporation,
subject to the control of the Board of Directors, except the Vice Presidents,
the Secretary, the Assistant Secretary, the Treasurer and the Assistant
Treasurer. He shall generally conduct the affairs of the corporation, and shall
do and perform such other duties as from time to time may be assigned to him by
the Board of Directors.

      Section 5. Vice President. The Vice President shall perform all of the
duties and be vested with all of the authority of the President in case of a
vacancy in the office of President or in the absence of disqualification of the
President, and shall have such other powers and shall perform such other duties
as may be assigned to him by the Board of Directors. If there be more than one
Vice President, the Board of Directors may designate one of them as the Senior
Vice President and he shall perform all the duties and be vested with all the
authority set forth in the preceding sentence; and the other Vice President or
Vice Presidents shall have such other powers and shall perform such other duties
as may be assigned to him or them by the Board of Directors.

      Section 6. Secretary. The Secretary shall keep the minutes of all meetings
of the Board of Directors and the shareholders. The Secretary shall likewise
attend to the giving and serving of all notices of meetings, and shall affix the
seal of the corporation to all certificates of stock and all authorized
contracts and obligations of the corporation, and shall attest the same, and
shall keep the transfer books and ledgers of the corporation, which books shall
be at all reasonable times, open for examination to any director, and he shall
in general perform all of the duties incident to the office of the Secretary,
and shall have such other powers and duties as shall be from time to time
conferred upon him by the Board of Directors.

      Section 7. Assistant Secretary. The Board of Directors may designate and
choose an Assistant Secretary, who shall have the usual powers and duties
pertaining to his office together with such other powers and duties as may be
assigned to him by the Board of Directors. In case of the absence or disability
of the Secretary, the duties of the Secretary shall be performed by the
Assistant Secretary.

      Section 8. Treasurer. The Treasurer shall have the custody of all the
funds and securities of the corporation, and shall have the power to sign checks
and drafts of the corporation, and any depository in which the funds of the
corporation are deposited shall be conclusively protected in honoring and acting
upon any check or draft signed by the Treasurer. The treasurer shall keep full
and accurate account of all
<PAGE>

moneys received and paid on account of the corporation which shall truly reflect
all of the financial transactions and conditions of the corporation, and shall
conform to the requirements of Article V hereof, and he shall generally perform
all acts incident to the position of Treasurer, and shall have such further
powers and duties as shall be from time to time conferred upon him by the Board
of Directors.

      Section 9. Assistant Treasurer. The Board of Directors may designate and
choose an Assistant Treasurer, who shall have the usual powers and duties
pertaining to his office together with such other powers and duties as may be
assigned to him by the Board of Directors. In case of the absence or disability
of the Treasurer, the duties of the Treasurer shall be performed by the
Assistant Treasurer.

      Section 10. Absence or Inability to Act. In the case of absence or
inability to act of any officer of the corporation and of any person herein
authorized to act in his place, the Board of Directors may from time to time
delegate the powers or duties of such officer to any other officer, or any
director or other person whom it may select.

                                    ARTICLE V

                                Corporate Records

      Section 1. Corporate Records. The directors and officers of the
corporation shall keep accurate account of the corporate transactions. The books
and records of the corporation shall at all times be subject to examination by
any director or by any committee appointed for the purpose at a meeting of the
shareholders, or by the holders of at least one-tenth of the stock outstanding
not in a meeting. The minutes and resolutions of the Board of Directors shall at
all times be open to examination by any member of the Board or by any committee
appointed by the shareholders, and such minutes shall be produced whenever
required by the shareholders at any meeting. The books of the corporation shall
be so kept as to show at all times what money or other consideration was
received by the corporation for the stock issued by it and the number of shares
issued.

                                   ARTICLE VI

                              Dividends and Finance

      Section 1. Dividends. The Board of Directors may from time to time declare
and pay dividends of so much of the net profits of the corporation as they deem
it prudent to divide, payable in cash or other property of the corporation,
against its accumulated earnings or surplus, whenever such declaration of
dividends will not impair the capital of the corporation.
<PAGE>

      Section 2. Depository of Funds. The moneys of the corporation shall be
deposited in the name of the corporation in such bank or banks or trust company
or trust companies as the Board of Directors shall designate, and shall be drawn
out only by check, signed by persons designated by resolution of the Board of
Directors.

      Section 3. Fiscal Year. The fiscal year of the corporation shall begin on
the first day of _____ in each year, unless otherwise provided by the Board of
Directors.

                                   ARTICLE VII

                                 Corporate Seal

      Section 1. Corporate Seal. The corporate seal of this corporation shall be
circular in form and shall have inscribed thereon the name of this corporation
and the words "Corporate Seal" in the center, and for this purpose hereby adopts
the seal the impression of which is made on the margin hereof.

                                  ARTICLE VIII

                               Amendment to Bylaws

      Section 1. Amendment to Bylaws. These Bylaws may be altered, amended or
repealed in whole or in part at any meeting of the Board of Directors by the
affirmative vote of a majority of the directors present at the meeting, a quorum
being present, subject to repeal or change by the affirmative vote of the
holders of a majority of the issued and outstanding shares then entitled to
vote, at any meeting of the shareholders.