APA (7th ed.) Citation

United States. Post Office Department. (1931). General scheme of distribution for city of Portland, Oreg. GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. General Scheme of Distribution for City of Portland, Oreg. [Washington]: GPO, 1931.

MLA (9th ed.) Citation

United States. Post Office Department. General Scheme of Distribution for City of Portland, Oreg. GPO, 1931.

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