APA (7th ed.) Citation

United States. Post Office Department. (1924). U.S. official postal guide. GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. U.S. Official Postal Guide. [Washington]: GPO, 1924.

MLA (9th ed.) Citation

United States. Post Office Department. U.S. Official Postal Guide. GPO, 1924.

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