_:n7c96c4094ed34fafa1109cbe132838e6xb2
<http://schema.org/text>
"<p>ISBN(International Standard Book Number) is a 10 or 13-digit unique identifier for books found on the back cover or copyright page.  1970-2007 each published book has a 10-digit format of 9-digit numeric + [1-digit numeric or character 'X' check digit], for example, <i>0-936385-40<b>5</b>, 0-8044-2957-<b>X</b></i>.\n<br><small>FYI 'X' actually means '10' in ISBN, and you, as a book buyer, could ignore all the hyphens '-'. </small></p>\n<p>\nOn Jan 1, 2007, they began the changeover to 13 digits number starting with the prefix '<b>978</b>' or '<b>979</b>', for instance, '<i>9780804429573</i>'.  If you find both 10 and 13-digit ISBN number on the book cover, both are valid to use. \n\n</p>"
<https://www.addall.com/isbn/>