Letter Agreement regarding Subscription Agreement and Plan of Merger

February 8, 2007

I&L Holdings, Inc.

I&L Operating LLC

Cambridge Scientific Abstracts, Limited Partnership

c/o Cambridge Information Group, Inc.

7200 Wisconsin Ave, Suite 601

Bethesda, MD 20814

Attn: Larisa Avner Trainor

Fax: 301-961-6790

Dear Larisa:

Reference is hereby made to that certain Subscription Agreement and Plan of Merger, dated as of December 14, 2006 (the “ Agreement ”), by and among ProQuest Information and Learning Company, a Delaware corporation (the “ U.S. Company ”); I&L Holdings, Inc., a Delaware corporation (“ Buyer Parent ”); I&L Operating LLC, a Delaware limited liability company and wholly owned subsidiary of Buyer Parent (“ Buyer Sub ,” and with Buyer Parent, the “ Buying Parties ”); ProQuest Company (“ Parent ”), a Delaware corporation; ProQuest Canada/U.K. Holdings, LLC, a Delaware limited liability company and wholly owned subsidiary of Parent (“ Canada/U.K. LLC ”); and, solely for purposes of Article V and Section 12.1 of the Agreement, Cambridge Scientific Abstracts, Limited Partnership, a Maryland limited partnership (“ Guarantor ”). All capitalized terms used herein but not otherwise defined shall have the meanings given to them in the Agreement.

The following sets forth certain amendments to the Agreement hereby agreed to by the undersigned and the Buying Parties:

1.             Cash Balance . Parent will cause the Acquired Entities to have, as of the Closing Date, (a) no more than 2.5 million British Pounds of cash, (b) no more than $500,000 Canadian Dollars of cash, and (c) no more than the equivalent of US$2 million of cash in other non-U.S. currencies. When determining the final amount of the Closing Working Capital Value, any and all cash and cash accounts held by the Acquired Entities on the Closing Date shall be included in the definition of Current Assets used in the calculation of the Closing Working Capital Value. For purposes of calculating the Closing Working Capital Value, all cash in a currency other than U.S. dollars shall be converted into U.S. dollars at the average of the bid and ask rates found on the Yahoo! finance exchange web page as of 5:00 p.m. on the date of Closing.

2.             Issuance Price . The first sentence of Section 2.3(a) of the Agreement is hereby deleted in its entirety and replaced with the following sentence:

“The aggregate consideration in the Issuance for all of the Preferred Stock shall be $109,000,000 (the “ Issuance Price ”).”

3.             Purchase Price Allocation . Schedule 2.3 of the Agreement is hereby deleted in its entirety and replaced with a new Schedule 2.3 in the form attached hereto as Exhibit A .