APA (7th ed.) Citation

United States. National Park Service. (1939). Grand Canyon National Park, Arizona. [s.n.].

Chicago Style (17th ed.) Citation

United States. National Park Service. Grand Canyon National Park, Arizona. [Washington]: [s.n.], 1939.

MLA (9th ed.) Citation

United States. National Park Service. Grand Canyon National Park, Arizona. [s.n.], 1939.

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