ISBN Numbers & ISSN Numbers

The International Standard Book Number (ISBN) is a unique, numerical commercial book identifier, based upon the 9-digit Standard Book Numbering (SBN) code created in the UK by the booksellers and stationers W.H. Smith and others in 1966.The 10-digit International Standard Book Number (ISBN) format was developed by the International Organization for Standardization and published as an international standard, ISO 2108, in 1970; (however, the 9-digit SBN code was used in the UK until 1974). Currently, the ISO TC 46/SC 9 is responsible for the standard.

Since 1 January 2007, International Standard Book Numbers are of 13 digits, compatible with Bookland EAN-13s. Like the numeric identifier, the International Standard Serial Number (ISSN) identifies periodical publications such as magazines.
ISBN FAQ

http://books.google.co.in/books?id=I-RaByhWLisC&pg=PA82&lpg=PA82&dq=ISBN+NUMBERS&source=web&ots=9eGUdU8643&sig=NvyzEFmygGuZjdTPCaAtmiHpDm4&hl=en&sa=X&oi=book_result&resnum=8&ct=result#PPA84,M1

http://www.isbn.nielsenbookdata.co.uk/controller.php?page=158

you can search using ISBN in following websites

http://isbndb.com/

http://www.biblio.com/isbn/

http://en.wikipedia.org/wiki/Special:BookSources

Know How ISBN numbers are assigned

http://www.bowker.com/index.php/component/content/article/2