National Union Catalog in the context of Library catalog

A union catalog is a combined library catalog describing the collections of a number of libraries. Union catalogs have been created in a range of media, including book format, microform, cards and more recently, networked electronic databases. Print union catalogs are typically arranged by title, author or subject (often employing a controlled vocabulary); electronic versions typically support keyword and Boolean queries. Union catalogs are useful to librarians, as they assist in locating and requesting materials from other libraries through interlibrary loan service. They also allow researchers to search through collections to which they would not otherwise have access, such as manuscript collections.

The largest union catalog ever printed is the American National Union Catalog Pre-1956 Imprints (NUC), completed in 1981. This achievement has since been superseded by the creation of union catalogs in the form of electronic databases, of which the largest is OCLC's WorldCat. Other examples include K10plus in Germany, Library Hub Discover (formerly COPAC) provided by Research Libraries UK and AMICUS, provided by Library and Archives Canada.

Bulfinch's Mythology is a collection of tales from myth and legend rewritten for a general readership by the American Latinist and banker Thomas Bulfinch, published after his death in 1867. The work was a successful popularization of Greek mythology for English-speaking readers.

Carl J. Richard comments (with John Talbot of Brigham Young University concurring) that it was "one of the most popular books ever published in the United States and the standard work on classical mythology for nearly a century", until the release of classicist Edith Hamilton's 1942 Mythology: Timeless Tales of Gods and Heroes. By 1987, there were more than 100 editions of Bulfinch's Mythology in the National Union Catalog, and in a survey of amazon.com in November 2014 there were 229 print editions and 19 e‑books. Talbot opined that, of the many available, Richard P. Martin's 1991 edition is "by far the most useful and extensive critical treatment".