APA (7th ed.) Citation

United States Postal Service. (1984). Zip+4® codes, why they add up for business mailers. U.S. Postal Service.

Chicago Style (17th ed.) Citation

United States Postal Service. Zip+4® Codes, Why They Add Up for Business Mailers. [Washington, D.C.?]: U.S. Postal Service, 1984.

MLA (9th ed.) Citation

United States Postal Service. Zip+4® Codes, Why They Add Up for Business Mailers. U.S. Postal Service, 1984.