The Monthly Catalog of United States Government Publications, with records from January 1994 to the present, is available via the Web. Records are searchable by title, publication year, Superintendent of Documents Class Number, Depository Item Number, and GPO (Government Printing Office) Sales Stock Number. Once your item has been retrieved, you can use the site to locate the nearest federal depository library where it is available, as well as the nearest GPO Book Store where it can be purchased. Help on the searching system and the searchable fields is available on the home page.
http://www.access.gpo.gov/su_docs/dpos/adpos400.html