United States. National Park Service. (1970). Compilation of the administrative policies for the national parks and national monuments of scientific significance (natural area category) (Rev. 1970.). For sale by the Supt. of Docs., U.S. Govt. Print. Off.
Cita Chicago (17th ed.)United States. National Park Service. Compilation of the Administrative Policies for the National Parks and National Monuments of Scientific Significance (natural Area Category). Rev. 1970. Washington: For sale by the Supt. of Docs., U.S. Govt. Print. Off, 1970.
Cita MLA (8th ed.)United States. National Park Service. Compilation of the Administrative Policies for the National Parks and National Monuments of Scientific Significance (natural Area Category). Rev. 1970. For sale by the Supt. of Docs., U.S. Govt. Print. Off, 1970.