Associations Unlimited (Gale) This link opens in a new windowOn advanced search page, "Select Series" to limit search to the three titles in the Encyclopedia of Associations series. The premier source for associations - use this database to locate approximately 460,000 international and U.S. national, regional, state, and local nonprofit membership organizations in all fields, including IRS data on U.S. 501(c) nonprofit organizations. The database is also used to monitor association trends; identify related associations; networking and making professional contacts; marketing to associations, their members and markets.