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Library of Congress

Preassigned Control Number Program

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Preassigned Control Number Program


Note: The United States ISBN Agency will soon begin assigning ISBNs starting with the prefix element 979 (in addition to the ISBNs with prefix element 978 currently assigned).

Prior to 2007, the ISBN was 10 digits in length. In January 2007, the 13-digit ISBN launched to increase the capacity of the ISBN system. To date, 13-digit ISBNs assigned by the U.S. ISBN Agency include the 978 prefix, which allowed systems to contain both 10- and 13-digit ISBNs for all books. However, a 13-digit ISBN starting with 979 does not have an equivalent 10-digit ISBN. Once this change takes place, only 13-digit ISBNs starting with 978 or 979 should be used to identify a book.

Questions? Bowker is happy to help. Please contact [email protected].

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