Find the bar code on the back book cover. The ISBN should be listed across the top of the bar code after the abbreviation "ISBN" and a colon. If your book is a hardcover book and the jacket is missing, you may also find the ISBN on the copyright page of the book (this is the page after the title page that tells you when the book was published, along with who published it and where).
Look for the number or numbers at the beginning of the ISBN. This number is the group identifier, a one- to five-digit number representing a national or geographic group of publishers. For example, the digits 0 or 1 identify books published in English-speaking countries, whereas 99936 would signify a book published in Bhutan. For books published after 2007, the group identifier is the number after the 978 or 979 and the first hyphen in the ISBN. A list of group identifiers is available at the International ISBN Agency website (see Resources).
Search for the next set of numbers between hyphens. This is the publisher code, the number used to identify a particular publisher within a group. Publishers purchase publisher codes in blocks, and may purchase additional blocks as needed. Should you want to look up the publisher code for a particular publisher, you would need to purchase The Publisher's International ISBN Directory, as no comprehensive list of publisher codes exists online.
Identify the second set of numbers between hyphens after the publisher code. This number is the title identifier given to a particular title or edition of a title. A hardcover and paperback edition of the same title will have two different title identifier numbers.
Look for the single digit at the end of the ISBN (after the publisher code). This digit is known as the check digit, and it validates the ISBN. The check digit must range from 0 to 10, with an upper case X appearing as the check digit rather than the numeral 10.