1. American National Standards Institute. American national standard for protective headgear—for bicyclists. ANZI Z90.4-1984. Washington, DC, 1984.
2. American Society for Testing and Materials. Standard Specification for Protective Headgear Used in Bicycling, F 1447-93. Philadelphia, 1993.
3. American Society for Testing and Materials. Standard Specification for Protective Headgear Used in Bicycling, F 1447-94. Philadelphia, 1994.
4. ASTM International. Standard Specification for Protective Headgear Used in Bicycling, F 1447-99a. West Conshohocken, 1999
5. ASTM International. Standard Specification for Helmets Used in Recreational Bicycling or Roller Skating, F 1447-02. West Conshohocken, 2002