Scott Boren has a great look at electronic searching of the full-text of books. He covers Several Book Search Web Sites, Text Archives for older materials, Proprietary Book Search sites, some Smaller Collections, Google Book Search, some Emerging Projects, and some sites for Further Reading.
Electronic searching of the full-text of books goes beyond the index and table of contents to search for any and all text in one book or in many. A phrase, number, word, or any string of characters can be searched. A9 same book database as Amazon, Google Book Search, and Live Search Books can all Search Inside The Book, or search inside many books at once. The book search sites listed in this paper are available free of charge, with the exception of "Two Proprietary Book Search Products below." As Greg Notess pointed out at the Computers in Libraries conference on April 18, 2007 (hereafter Notess 2007, April), another use of book search is to verify citations and to find mentions of passages as when a patron brings a photocopied chapter and asks "What book does this come from? I need to find the source" Or when was a particular word, number, or phrase mentioned? (For early mentions of words, the Oxford English Dictionary is also good.) -- Read More