Useful Sources of Information
International ISBN Agency
http://www.isbn-international.org/
Information about
EAN.UCC.GTIN
http://www.gs1.org/productssolutions/
Information about DOI
http://www.doi.org
Information about URN
http://www.ietf.org/rfc/rfc2611.txt
EDItEUR
http://www.editeur.org
