1. Protective helmets for vehicle user;British Standards Institution,1985
2. Effect of polystyrene foam density on motorcycle helmet shock absorption;Gale;Plastics & Rubber Processing & Applic.,1985
3. Der schultzhelm als passives Sicherheitselement;Grandel,1987
4. NOCSAE football helmet certification program;Hodgson;Med. Sci. Sports,1975
5. Helmets: a new look at design and possible protection;Hopes,1989