APA (7th ed.) Citation

United States. Post Office Department. (1938). Postal bulletin, July 18, 1938. [s.n.].

Chicago Style (17th ed.) Citation

United States. Post Office Department. Postal Bulletin, July 18, 1938. [Washington]: [s.n.], 1938.

MLA (9th ed.) Citation

United States. Post Office Department. Postal Bulletin, July 18, 1938. [s.n.], 1938.

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