Books in print.com
Complete bibliographic, book ordering and subject classification information over 3.4 million books, along with 600,000 full text reviews of many of these books.
Ulrichs Periodical Directory Online
Provides information on virtually every active and ceased periodical, annual, irregular publication, and monographic series published in the United States and throughout the world.
Union catalog of materials held by OCLC libraries. 49,000,000+ bibliographic records for audio-visual materials, books, maps, musical scores, newspapers, periodicals and more.