Libraries
Currently, the book catalogs of major research libraries around the world are free and open to the public. Interlibrary loans through a local library or even purchasing them a bookstore or publisher, are two efficient ways to get your hands on a book.

• OCLC Worldcat
• Library of Congress
• Library and Archives Canada 
• British Library. Look under the "Catalogues" tab
• Bibliothecque Nationale de France. Can be searched in English. Most holdings are, of course, en francais.
• Deutsche National Bibliothek. Main catalog of the German National Library. (Can be searched in English.)

Online Bookstores
Vast online bookstores such as Amazon.com or Barnes and Noble carry thousands of titles searchable by author, title, and sometimes keyword. Here is a sampling of the many online bookstores available.

• Abebooks
• Alibris
• Amazon.com
• Barnes and Noble
• Powell's Books
• U.S. Government Bookstore. Allows direct purchase of government publications and other information products. For more information, please see the tab on Government Documents.