these fifty-stamp sheets. (See below image, right) See also Postage stamps and postal history of the United States Revenue stamps of the United States Presidents of the United States on U.S. postage stamps Postage stamps and postal history of Panama History of Panama U.S. Postage stamp locator Notes References Bibliography Stanley Gibbons Ltd: various catalogues AskPhil – Glossary of Stamp Collecting Terms Encyclopaedia of Postal History External links The first stamps of the Canal Zone. Canal Zone Study Group Panama Canal Zone Philately of Panama Canal Zone