References
- FHWA (Federal Highway Administration) . Highway Statistics Available at: http://www.fhwa.dot.gov/policyinformation/statistics.cfm. Accessed October 31, 2012
- NHTS (National Travel Household Survey) . 2011 . Summary of Travel Trends: 2009 National Household Travel Survey , Washington , DC : Federal Highway Administration .
- NPTS (National Personal Transportation Study) . 1973 . Characteristics of Licensed Drivers , Washington , DC : Federal Highway Administration .
- Sivak , M and Schoettle , B . 2011 . Recent changes in the age composition of US drivers: implications for the extent, safety, and environmental consequences of personal transportation . Traffic Inj Prev , 12 : 588 – 592 .
- Sivak , M and Schoettle , B . 2012a . Note: The changing gender composition of US drivers . Traffic Inj Prev , 13 : 575 – 576 .
- Sivak , M and Schoettle , B . 2012b . Update: percentage of young persons with a driver's license continues to drop . Traffic Inj Prev , 13 : 341