APA (7th ed.) Citation

United States Postal Service. (1987). International priority airmail. U.S. Postal Service.

Chicago Style (17th ed.) Citation

United States Postal Service. International Priority Airmail. [Washington, D.C.?]: U.S. Postal Service, 1987.

MLA (8th ed.) Citation

United States Postal Service. International Priority Airmail. U.S. Postal Service, 1987.

Warning: These citations may not always be 100% accurate.