1. “;Report of the 65th General Motors Stockholders Meeting,” Detroit, May 25, 1973
2. “;Report by the Committee on Motor Vehicle Emissions,” National Academy of Sciences, Washington, D.C., Feb. 15, 1973
3. Annual Report, p. 212. Council on Environmental Quality, Washington, D.C., 1971
4. “;Statistical Abstract of the U.S.” Bureau of Census, Washington, D.C., 1972