APA

U. S. Department of the interior. National Park Service, United States, . (1972). National environmental study area. [Washington, D.C.?]: U.S. Dept. of the Interior, National Park Service, Office of Environmental Interpretation.

Chicago

U. S. Department of the interior. National Park Service, United States, . 1972. National environmental study area. [Washington, D.C.?]: U.S. Dept. of the Interior, National Park Service, Office of Environmental Interpretation.

Harvard

U. S. Department of the interior. National Park Service, United States, . (1972). National environmental study area. [Washington, D.C.?]: U.S. Dept. of the Interior, National Park Service, Office of Environmental Interpretation.

MLA

U. S. Department of the interior. National Park Service, United States, . National environmental study area. [Washington, D.C.?]: U.S. Dept. of the Interior, National Park Service, Office of Environmental Interpretation. 1972.