The LCCN or PCN is a number that is assigned to your book and appears on the copyright page. This is the reference number that is found on your book’s Library Catalog Card for location. This number is important if you are looking to sell your books to libraries and is best to apply for before your book is published so it can go on the copyright page.
Contact the Copyright Office at http://www.LOC.gov or http://www.copyright.gov
There is an application and account set up that needs to be done http://ecip.loc.gov/pls/ecip/pub_signon?system=pcn and http://pcn.loc.gov/pcn/pcn077.html
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