Google is sending subpoenas to Microsoft and Yahoo as part of its legal defense in a copyright lawsuit brought against it by authors and publishers.
In addition, Google will subpoena documents from Amazon, Random House and the Association of American Publishers and agree to keep confidential files under a protective order, according to the San Jose Mercury News.
The lawsuit filed last October by the Association of American Publishers revolves around Google Print. The plan is to digitize large parts of the book collections of the University of Michigan, Harvard University, Stanford University, the New York Public Library and Oxford University. Google plans to let people search the texts and sell advertisements related to such searches.