Online catalogs

Authority files

Library of Congress

Library of Congress online catalog
- The national union catalog (NUC), pre-1956 imprints: a catalog of photocopies of printed catalog cards for books cataloged by the Library of Congress and other American and Canadian libraries

National library catalogs

National Library of Australia
Bayerische Staatsbibliothek (BSB)
National Library of Canada (AMICUS)
European library catalog portal
National Library of the Czech Republic
Catalogue Collectif de France (CCFR): unified search interface for libraries in France
Indice SBN (Il Servizio Bibliotecario Nazionale): union catalog of libraries in Italy
Karlsruher Virtueller Katalog: simultaneous search for books and serials in libraries of the region of Karlsruhe
Karlsruher Virtueller Katalog (English interface): simultaneous search of library catalogs from Germany, Austria, and Switzerland, as well as major catalogs worldwide
COPAC (Consortium of University Research Libraries): access to the merged online catalogs of the largest university research libraries in the UK, includding the British Library and the National Library of Scotland

Yale University Library