Five of the world's largest libraries have joined Google in a herculean effort to digitize millions of books and make every sentence searchable. The project involves libraries at Harvard and Stanford Universities, the University of Michigan at Ann Arbor, and the University of Oxford, in England, as well as the New York Public Library. It could turn Google into the single largest holder of digitized published material, while providing researchers and students with an unprecedented tool for finding information. Once finished, the digital repository could help researchers identify links among materials or discover books they would never have found by traditional methods. The project could greatly increase access to books, since people will be able to call up many books online rather than having to make a trip to a library to read them. Some librarians see the deals as a major boon for libraries and patrons--and a way to raise the public's awareness of the materials that can be found in the stacks.