1. The Clean Air Act as amended August 7, 1977. Public Law 95–95. U. S. Govt. Printing Office, Washington, D.C.
2. Protection against Visibility Impairment Under the Clean Air Act
3. Visibility Regulations
4. “Managing Air Quality and Scenic Resources at National Parks and Wilderness Areas.”;Rowe,1983
5. “Optics of the Atmosphere,”;McCartney,1976