APA (7th ed.) Citation

United States. National Park Service. (1938). 1937 Yearbook: Park and recreation progress. [s.n.].

Chicago Style (17th ed.) Citation

United States. National Park Service. 1937 Yearbook: Park and Recreation Progress. [Washington]: [s.n.], 1938.

MLA (9th ed.) Citation

United States. National Park Service. 1937 Yearbook: Park and Recreation Progress. [s.n.], 1938.

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