WorldCat information system contains all kinds of materials, including books, periodicals, music, videos, maps and so on. The data collected come from the collections of more than 8000 libraries around the world/kloc-0.

Worldcat is OCLC's online cataloging joint catalogue. Worldcat is a joint cataloguing library of libraries and other materials all over the world, and it is also the largest online bibliographic database in the world.