APA (7th ed.) Citation

United States. National Park Service. (1938). Purpose and policy. [s.n.].

Chicago Style (17th ed.) Citation

United States. National Park Service. Purpose and Policy. [Washington]: [s.n.], 1938.

MLA (9th ed.) Citation

United States. National Park Service. Purpose and Policy. [s.n.], 1938.

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