APA (7th ed.) Citation

United States. Forest Service. (1931). Directory, Forest Service. GPO.

Chicago Style (17th ed.) Citation

United States. Forest Service. Directory, Forest Service. [Washington]: GPO, 1931.

MLA (9th ed.) Citation

United States. Forest Service. Directory, Forest Service. GPO, 1931.

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