With author cards, the main entry is the author's name. This information appears at the top of the card. In the case of single authors, the last name appears first, followed by a comma and the author's first name. Author cards for books with two or more authors include information on the additional authors; however, their names appear "First name, Last name." If the author is a business, government or organization, the name of this entity appears at the top of the card. Librarians then alphabetized these cards by the author's last name.
With title cards, the main entry is the title of the book. The full title, taken directly from the title page, appears at the top of the card. Librarians alphabetized these cards by the first word of the title after omitting articles such as "the," "a" and "an."
Subject cards begin with the subject of the book placed at the top of the card. In the United States, the Library of Congress supplies a list of applicable subject headings. The purpose of this list is to ensure a standardized means for different libraries to catalog their holdings. Because books often deal with more than one subject, each book can have multiple subject cards.
Author, title and subject cards include a lot of additional information. Publication information includes the city, name of the publisher, year of publication and International Standard Book Number (ISBN). The book's size and number of pages follow the publication information. If a book contains illustrations, a bibliography and/or an index, this information appears on the card. To help library users locate the book in the library, the book's call number is printed in the upper left-hand corner of the card.