a union list of serials held by libraries in the United States and Canada / Library of Congress, Cataloging Distribution Service. Prepared by the Serial Record Division of the Library of Congress. - [Monatsausgabe]. - Washington, DC : Libr. of Congress, Cataloging Distribution Service. - 29 cm. - Es erscheinen auch weitere kumulierende Ausg. - Neueste Ausg. (und frühere Bd.) ; ISSN 0028-6680