ISBN's - EIN's, Identifier"s - Copyright - LOC - Library of Congress

https://www.myidentifiers.com

http://isbn.org/helpful_links

ISBN.org [Bowker]

http://www.bookwire.com/ForPublishers -BONUS for ISBN purchases.

Bowker has more than just ISBN's:

1. http://www.bowker.com/en-US/products/
2. http://www.selfpublishedauthor.com/
3. http://www.bowker.com/en-US/products/literature/servprodlit_default.shtml