WorldCat Combined catalog describing over 360 million books, periodicals, sound recordings, videos, musical scores, archival materials, maps, electronic resources, and much more, in 470 different languages. Shows what materials are held by over 25,000 libraries worldwide (including most libraries in North America, 40 national libraries, and selected libraries from 170 countries worldwide). Incorporates all records from the former Research Libraries Group (RLG) Union Catalog (also known as RLIN, the Research Libraries Information Network).