These databases attempt to list all that exists in each sphere.
- WorldCat: over 179 million items from libraries worldwide, including books, whole journals, music, computer programs, etc., from 1000 AD to present. Covers all significant libraries in the U. S. and Canada plus a generous number from all other parts of the globe. Important to doctoral students for gaining bibliographic control. See the "Dissertations" tab also.
- HathiTrust: fully searchable e-books digitized from many books of earlier centuries through 1923, including page images, because these are now in the public domain. More recent books that are still under copyright can be searched for occurrence of search terms, yielding page numbers, but the pages cannot be viewed. HathiTrust is a joint project of the Big Ten, the University of Chicago, the University of California system, and more recent members, to establish a repository of digitized collections.
- Associations Unlimited: information on 450,000 international and U.S. national, regional, state, and local nonprofit organizations in all fields. Many of these associations encourage research by publishing research guides and bibliographies and by facilitating access to grey literature.
- Ulrich's Periodicals Directory: bibliographic and access information for over 240,000 current periodicals from around the world. Entries provide pricing, subscription and distribution details as well as publisher & editor contacts. Direct links to URLs and e-mail addresses when available, along with nearly 8,000 reviews excerpted from Magazines for Libraries and Library Journal.