Estados Unidos. Department of the Interior. National Park Service. (1970). Compilation of the administrative policies: For the national parks and national monuments of scientific significance [natural area category]. National Park Service, Department of the Interior.
Cita Chicago Style (17a ed.)Estados Unidos. Department of the Interior. National Park Service. Compilation of the Administrative Policies: For the National Parks and National Monuments of Scientific Significance [natural Area Category]. Washington: National Park Service, Department of the Interior, 1970.
Cita MLA (8a ed.)Estados Unidos. Department of the Interior. National Park Service. Compilation of the Administrative Policies: For the National Parks and National Monuments of Scientific Significance [natural Area Category]. National Park Service, Department of the Interior, 1970.