APA (7th ed.) Citation

United States. National Park Service & National Conference on State Parks. (1938). Yearbook, park and recreation progress. U.S. G.P.O..

Chicago Style (17th ed.) Citation

United States. National Park Service and National Conference on State Parks. Yearbook, Park and Recreation Progress. Washington: U.S. G.P.O., 1938.

MLA (9th ed.) Citation

United States. National Park Service and National Conference on State Parks. Yearbook, Park and Recreation Progress. U.S. G.P.O., 1938.