The British Library's main catalog, which includes nearly 57 million items. This also includes links to the archives and manuscripts collections as well several other specialized catalogs in the library's collection.
This 2015 survey of more than 75 repositories in the Chicago area, sponsored by the Terra Foundation for American Art, allows you to browse archival holdings on American Art by respository, or to search across more than 900 records to locate information related to American Art in Chicago collections.
Search across the catalogs of more than 70 UK research libraries, including the British Library, the libraries of the British Museum, the Courtauld, the National Portrait Gallery, the Tate, and the Victoria and Albert.
This online portal offers quick and easy access to the collections of 48 leading European national libraries and research collections. It includes over 20 million digital items and over 125 million bibliographic records.
This union catalog indicates which of more than 1,100 libraries in the United States and Canada hold specific printed materials published prior to 1956. A table of contents to the 754-volume set is available here.