Libraries and Library Catalogs
- The British Library Catalogues
- The Bodleian Library Catalogues (Oxford University, UK)
- Dumbaraton Oaks Public Access Catalog (ACORN)
- Gateway to Europe's National Libraries (GABRIEL)
- Harvard University Library Catalogs
- Library of Congress Catalogs
- New York Public Library Catalogs
- Russian National Library (RNB — St. Petersburg)
- Russian State Library (RGB — Moscow)
- Southeastern Pennsylvania Theological Library Association (SEPTLA)
- Vatican Library