1. AAMA, 1997, http://www.aama.com/environment/gasoline.html
2. Caltrans, 1989, California Motor Vehicle Stock, Travel, and Fuel Forecast, Division of Transportation Planning, California Department of Transportation, Sacramento, California
3. CARB, 1989a, Data files for 1989 for Lead in Gasoline, California Air Resources Board, Sacramento, California
4. CARB, 1989b, California Air Resources Board refinery surveys, Lead in Gas (Paragarph D)—Quarterly Report 1989, California Air Resources Board, Sacramento, California
5. CARB, 1989c, California Air Quality Data, Summary of 1989 Air Quality Data, Gaseous and Particulate Pollutants, Technical Support Division, California Air Resources Board, Annual Summary, Vol. XXI, Sacramento, California