Help:ISBN

Many Wikipedia articles have an International Standard Book Number (ISBN) alongside the bibliographical entry for each book. Clicking on the linked 10- or 13-digit number links to WP:Book sources. This shows whether the particular book is listed in a library catalogue, at WorldCat, at Google Books, at major booksellers, or at other websites.

An example of a bibliographical entry as a reference or a suggestion for further reading would look like this:

The ISBN might lack hyphens between the digits, or it might contain spaces between the digits. Either way it should provide the link to WP:Book sources. Note that different editions of the same book may have different ISBNs. Also, books published prior to the 1970s do not have ISBNs, unless subsequently reprinted.