WorldCat is a union (i.e. collective) catalog of records of any type of material (books, periodicals, scores, films, recordings, etc.) cataloged by over 41,000 OCLC (Online Computer Library Center) member libraries, primarily but not exclusively, from libraries in the United States, but extending to 82 other nations. There are more than 47 million records in the WorldCat database, whose scope includes everything from Babylonian inscriptions to e-books. This database is used to verify citations of items not found in the HOLLIS Catalog, possibly to find a local holding library, or to provide accurate citations for interlibrary loan requests. OCLC adds evaluative content to WorldCat bibliographic records such as tables of contents, cover art, book summaries, and notes about authors. A search for archives and manuscripts should include ArchivesUSA and Archive Grid (both Harvard Libraries E-Resources) as well as WorldCat.