APA (7th ed.) Citation

United States. National Park Service. (1944). A Guide to the Geology of Rocky Mountain National Park [Colorado]. [s.n.].

Chicago Style (17th ed.) Citation

United States. National Park Service. A Guide to the Geology of Rocky Mountain National Park [Colorado]. [Washington]: [s.n.], 1944.

MLA (9th ed.) Citation

United States. National Park Service. A Guide to the Geology of Rocky Mountain National Park [Colorado]. [s.n.], 1944.