I\'ve got ISBN numbers (10-digits and 13 digits) without the dashes. Now I\'m looking for a way to add those dashes automatically.
I found some useful information here:
You can deduce the length of the publisher identifier if you have the full range tables.
Example 1. ISBN 0141439564 (Penguin: Great Expectations)
Example 2. ISBN 2253004227 (Poche: Gérminal)
You can check your algorithm at the Library of Congress's ISBN hyphenation tool.