1. Goodwin A, Kirley B, Sandt L, Hall W, Thomas L, O’Brien N, Summerlin D. Countermeasures that work: A highway safety countermeasures guide for State Highway Safety Offices. 7th edition. (Report No. DOT HS 811 727). Washington, DC: National Highway Traffic Safety Administration; 2003.
2. Kraus JF, Peek C, McArthur DL, Williams A. The effect of the 1992 California motorcycle helmet use law on motorcycle crash fatalities and injuries. JAMA. 1994;272(19):1506–11.
3. Fatality Analysis Reporting System: 2011. Washington, DC: National Highway Traffic Safety Administration, U.S. Department of Transportation. (Accessed July 23, 2013, at http://www-fars.nhtsa.dot.gov/Main/index.aspx).
4. Traffic Safety Facts 2010 Data: Motorcycles. Washington, DC: National Highway Traffic Safety Administration, U.S. Department of Transportation, 2012. (Accessed July 24, 2013, at http://www-nrd.nhtsa.dot.gov/Pubs/811639.pdf ).
5. Cook LJ, Kerns T, Burch C, Thomas A, Bell E. Motorcycle helmet use and head and facial injuries: Crash outcomes in CODES-linked data. Washington: National Highway Traffic Safety Administration, U.S. Department of Transportation; 2009 (Accessed July 23, 2013http://www-nrd.nhtsa.dot.gov/pubs/811208.pdf).