APA (7th ed.) Citation

United States. Post Office Department. (1931). Domestic postage rates, et cetera, effective Aug. 1931. GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. Domestic Postage Rates, Et Cetera, Effective Aug. 1931. [Washington]: GPO, 1931.

MLA (9th ed.) Citation

United States. Post Office Department. Domestic Postage Rates, Et Cetera, Effective Aug. 1931. GPO, 1931.

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