APA-referens (7:e uppl.)

United States Postal Service. (1994). 1994 [i.e. one thousand, nine hundred and ninety four] commemorative stamp collection. U.S. Postal Service.

Chicago-referens (17:e uppl.)

United States Postal Service. 1994 [i.e. One Thousand, Nine Hundred and Ninety Four] Commemorative Stamp Collection. México: U.S. Postal Service, 1994.

MLA-referens (8:e uppl.)

United States Postal Service. 1994 [i.e. One Thousand, Nine Hundred and Ninety Four] Commemorative Stamp Collection. U.S. Postal Service, 1994.