1. Iowa Department of Transportation. Iowa driver's Manual, p. 56,
2. Ofice of Driver Services, Iowa Department of Transportation, personal communication.
3. Idaho Department of Motor Vehicles. Idaho Driver's Manual. Boise, Idaho: Idaho Transportation Department, Division of Motor Vehicles, 2001, section 8, page 4. (www2.state.id.us/itd/dmv/driverservices/ds_forms.htm)
4. North Carolina Department of Motor Vehicles. North Carolina Driver's Manual. Sample test question # 8.
5. National Highway Traffic Safety Administration Center for Statistics and Analysis (199). Cited in www.jointogether.org
6. Department of Public Safety, Driver License Division. Utah Driver Handbook. Salt Lake City, Utah: Department of Public Safety, Driver License Division, 2002, p. 62.
7. Department of Motor Vehicles. Vermont Driver's Manual: Doing More for Vermont. Montpelier, Vermont: Agency of Transportation, Department of Motor Vehicles, 2001. p. 47; correct statistic reported by the Vermont Agency for Transportation, personal communication, 8/30/02.