APA (7th ed.) Citation

United States. Post Office Department. (1941). United States Official Postal Guide; Monthly Supplement to Parts I and II; May 1941. [s.n.].

Chicago Style (17th ed.) Citation

United States. Post Office Department. United States Official Postal Guide; Monthly Supplement to Parts I and II; May 1941. [Washington]: [s.n.], 1941.

MLA (9th ed.) Citation

United States. Post Office Department. United States Official Postal Guide; Monthly Supplement to Parts I and II; May 1941. [s.n.], 1941.

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