# Union catalog > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Union_catalog > Markdown URL: https://mediated.wiki/source/Union_catalog.md > Source: https://en.wikipedia.org/wiki/Union_catalog > Source revision: 1328443238 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Combined library catalog describing the collections of a number of libraries}} {{Use dmy dates|date=July 2021|cs1-dates=y}} A '''union catalog''' is a combined [library catalog](/source/library_catalog) describing the collections of a number of [libraries](/source/library). Union catalogs have been created in a range of media, including [book](/source/book) format, [microform](/source/microform), [card](/source/card_catalog)s and more recently, networked electronic [databases](/source/databases). Print union catalogs are typically arranged by title, author or subject (often employing a [controlled vocabulary](/source/controlled_vocabulary)); electronic versions typically support keyword and [Boolean](/source/Boolean_logic) queries. Union catalogs are useful to [librarian](/source/librarian)s, as they assist in locating and requesting materials from other libraries through [interlibrary loan](/source/interlibrary_loan) service. They also allow researchers to search through collections to which they would not otherwise have access, such as [manuscript](/source/manuscript) collections. The largest union catalog ever printed is the American ''[National Union Catalog Pre-1956 Imprints](/source/National_Union_Catalog)'' (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 This achievement has since been superseded by the creation of union catalogs in the form of electronic databases, of which the largest is [OCLC](/source/OCLC)'s [WorldCat](/source/WorldCat).Wakeling, Simon, Paul Clough, Lynn Silipigni Connaway, Barbara Sen, and David Tomás. “Users and Uses of a Global Union Catalog: A Mixed‐methods Study of WorldCat.Org.” ''Journal of the Association for Information Science and Technology'' 68, no. 9 (2017): 2166–81. Other examples include [K10plus](/source/K10plus) in Germany, [Library Hub Discover](/source/Library_Hub_Discover) (formerly [COPAC](/source/COPAC)) provided by [Research Libraries UK](/source/Research_Libraries_UK) and AMICUS, provided by [Library and Archives Canada](/source/Library_and_Archives_Canada). For academic publications, several [academic search engines](/source/academic_search_engines) exist to combine the [open data](/source/open_data) provided by [open archive](/source/open_archive)s through [OAI-PMH](/source/OAI-PMH), as well as records from publishers deposited in [CrossRef](/source/CrossRef) and other sources. They include [BASE](/source/BASE_(search_engine)), [CORE](/source/CORE_(research_service)) and Unpaywall, which indexes over 20 million [open access](/source/open_access) publications as of 2020. ==Historical development== The idea of sharing catalogue records among libraries is at least as old as the [French Revolution](/source/French_Revolution), when a cataloguing standard was published encouraging librarians throughout France to contribute to cataloguing the nation's books by writing records on the backs of [playing card](/source/playing_card)s and mailing them off to the home of the [national library](/source/national_library) in Paris.{{cite book |year=2017 |author=Library of Congress |title=The Card Catalog: Books, Cards, and Literary Treasures |isbn=978-1452145402 |oclc=953599088 |publisher=Chronicle Books |url=https://archive.org/details/cardcatalogbooks0000unse_u0u5 |url-access=registration}}{{rp|30-31}} The idea was thus common knowledge among librarians throughout the 19th century. Nonetheless, it was not until 1901 that the U.S. Library of Congress exchanged cards with the Boston Public Library, Harvard College Library, and the New York Public Library{{rp|194}} and also began a card publishing service to sell copies of its own catalog cards to public libraries throughout the U.S.{{rp|138-193}} Card catalogues grew huge during the next six decades. In the late 1960s, the development of [machine-readable](/source/machine-readable) cataloguing in [computer](/source/computer)ized and [programmable](/source/computer_programming) form via the [MARC standards](/source/MARC_standards) meant that union cataloguing from then onward could be done electronically instead of physically. == See also == * {{annotated link|OAIster}} * {{annotated link|SUNCAT}} * {{annotated link|Trove}} * {{annotated link|Universal Bibliographic Control}} * {{annotated link|UNIMARC}} * {{annotated link|Universal Decimal Classification}} * {{annotated link|Virtual International Authority File}} == References == {{Reflist|refs= {{Cite journal |title=The Proportion of NUC Pre-56 Titles Represented in OCLC WorldCat |author-last1=Beall |author-first1=Jeffrey |author-link1=Jeffrey Beall |last2=Kafadar |first2=Karen |author-link2=Karen Kafadar |date=2005 |journal=College & Research Libraries |volume=66 |issue=5 |pages=431–435 |doi=10.5860/crl.66.5.431 |doi-access=free}} {{Cite web |title=About AMICUS |url=http://www.collectionscanada.ca/amicus/006002-122-e.html |access-date=2016-11-01 |url-status=live |archive-url=https://web.archive.org/web/20161104004540/http://www.collectionscanada.ca/amicus/006002-122-e.html |archive-date=2016-11-04}} {{Cite journal |title=Unpaywall |author-last=Dhakal |author-first=Kerry |date=2019-04-15 |journal=Journal of the Medical Library Association |volume=107 |issue=2 |pages=286–288 |doi=10.5195/jmla.2019.650 |pmc=6466485}} }} {{Authority control}} Category:Library catalogues Category:Bibliography --- Adapted from the Wikipedia article [Union catalog](https://en.wikipedia.org/wiki/Union_catalog) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Union_catalog?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.