APA (7th ed.) Citation

United States. Post Office Department. (1911). Instructions to postmasters. GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. Instructions to Postmasters. [Washington]: GPO, 1911.

MLA (9th ed.) Citation

United States. Post Office Department. Instructions to Postmasters. GPO, 1911.

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