http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
historical catalog of U.S. stamp essays and proofs
The Omaha, trans-Mississippi issue, 1898
"Reprinted from the Collectors club philatelist with additions and corrections."
Trans-Mississippi and International Exposition (1898 : Omaha, Neb.)
Trans-Mississippi and International Exposition.
United States stamp essays and proofs, A historical catalog of