Advanced Book Exchange : world's largest source of out of print books, 12 million titles listed
Alibris : source for out-of-print and rare books
Amazon.com : online bookstore, offers 4.7 million books, CDs, audiobooks, etc.
Bibliofind: nine million used and rare books, periodical, and ephemera from thousands of booksellers
Gutenberg<e> : digital monographs reviewed by the American Historical Association and available online
Powell's Book Store : an inventory of over a million new and used books
Publishers' Catalogues Home Page : a comprehensive list of publishers worldwide
16 August 2014