International Standard Book Number in 1965, has – 340 indicating the publisher, 01381 their serial number, and 8 being the check digit. This can be converted to ; the check digit does not need to be re-calculated. Since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with "Bookland" European Article Number EAN-13s. An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January
International Standard Authority Data Number of an ISADN continues to be relevant to the information science community, as it could be a great help in the problem of measuring an individual author's research output. International Standard Authority Data Number The International Standard Authority Data Number (ISADN) was a registry proposed by the International Federation of Library Associations and Institutions (IFLA) to provide and maintain unique identifiers for entities described in authority data. Having such a unique number would have the benefits of being language-independent and system-independent. Francoise Bourdon was a major proponent of such a standard, proposing a structure for the ISADN and recommending that