WorldCat contains over 1.3 billion materials located in more than 10,000 libraries across the globe.
Union Catalogs identify material held in the collections of more than one library. The geographic area covered may vary from local to multinational. Use a union catalog when you need a comprehensive, rather that an SU-specific search. Use our interlibrary loan form to request materials that we do not own.
WorldCat - First Search: Over 36 million records of materials cataloged by OCLC member libraries. Includes manuscripts written as early as the 11th century. Updated daily.
COPAC: British Online Catalogue (Cambridge University, Edinburgh University, Glasgow University, Leeds University, and Oxford University)
MERLN (Military Education Research Library Network)
Libdex
A worldwide directory of library homepages, web-based OPACs, Friends of the Library pages, Web OPAC vendors and libraries using their software, and library e-commerce affiliate links.