Library Catalogs Union Catalogs -- See Union catalogs Here are entered catalogs of materials held in two or more libraries. When this heading is assigned to a catalog of special materials or works on a particular topic, a heading is also assigned for these materials or topics, e.g. 1. Technology--Bibliography--Union lists. 2. Catalogs, Union--France. --subdivisions Union lists under types of printed or non-book materials, e.g. Italian imprints--Union lists; and Bibliography--Union lists under subjects, e.g. Technology--Bibliography--Union lists