WorldCat in the context of "Bryn Mawr Classical Review"

A union catalog is a combined library catalog describing the collections of a number of libraries. Union catalogs have been created in a range of media, including book format, microform, cards and more recently, networked electronic databases. Print union catalogs are typically arranged by title, author or subject (often employing a controlled vocabulary); electronic versions typically support keyword and Boolean queries. Union catalogs are useful to librarians, as they assist in locating and requesting materials from other libraries through interlibrary loan service. They also allow researchers to search through collections to which they would not otherwise have access, such as manuscript collections.

The largest union catalog ever printed is the American National Union Catalog Pre-1956 Imprints (NUC), completed in 1981. This achievement has since been superseded by the creation of union catalogs in the form of electronic databases, of which the largest is OCLC's WorldCat. Other examples include K10plus in Germany, Library Hub Discover (formerly COPAC) provided by Research Libraries UK and AMICUS, provided by Library and Archives Canada.

OCLC, Inc. is an American nonprofit cooperative organization "that provides shared technology services, original research, and community programs for its membership and the library community at large". It was founded in 1967 as the Ohio College Library Center, then became the Online Computer Library Center as it expanded. In 2017, the name was formally changed to OCLC, Inc. OCLC and thousands of its member libraries cooperatively produce and maintain WorldCat, the largest online public access catalog in the world. OCLC is funded mainly by the fees that libraries pay (around $217.8 million annually in total as of 2021) for the many different services it offers. OCLC also maintains the Dewey Decimal Classification system.

K10plus is the union catalog of the German library networks GBV (Common Library Network) and SWB (Southwest German Library Network). It combines the catalogs of the majority of academic libraries in Germany.

K10plus combines the former union catalogs of GBV and SWB covering 10 of 16 states of Germany, the Prussian Cultural Heritage Foundation and other research institutions such as those of Leibniz Association, Helmholtz Association and Max Planck Society. As of March 2023, K10plus contained around 80 million bibliographic records, representing over 200 million physical and digital library assets from more than 1000 libraries. Large parts of K10plus are exported regularly into WorldCat and make up roughly 10% of it.