Cita APA (7a ed.)
United States Postal Service. History of the United States Postal Service: 1775-1993.
Cita Chicago Style (17a ed.)
United States Postal Service. History of the United States Postal Service: 1775-1993.
Cita MLA (9a ed.)
United States Postal Service. History of the United States Postal Service: 1775-1993.
Precaución: Estas citas no son 100% exactas.