The National Union Catalog of Pre-1956 Imprints, a set of 754 volumes, largely superseded the older Library of Congress Catalog of printed books, and included printed works published before 1956 which are held by major American and Canadian libraries. It is sometimes referred to as "the Mansell", after its publisher. This set is a massive bibliography compiled during the period from 1968 to 1981. It contains photocopies of printed catalog cards from major American and Canadian libraries, arranged alphabetically by author's last name, or by title for books that have no author, such as the Bible.