References
ETF (Eno Transportation Foundation, Inc.). 1994. Transportation in America, 12th Edition. Landsdown, Virginia: ETF.
FHWA (Federal Highway Administration). 1993. Highway Statistics 1992. FHWA-PL-93-023. Washington, D.C.: U.S. Department of Transportation.
PNGV (Partnership for a New Generation of Vehicles). 1994. Program Plan. Washington, D.C.: PNGV.
The White House. 1993. Historic Partnership Forged with Auto Makers Aims for 3-Fold Increase in Fuel Efficiency In as Soon as Ten Years. The White House, Office of the Press Secretary. September 29.