1. Aldman B, Balldin U, Gustafsson H, Nygreen A, Sporrong A, Astrand I. Carbon dioxide retention inside motorcycle helmets. 1981 International IRCOBI Conference on the Biomechanics of Impacts. Salon de Provence, France, September 8–10, 1981.
2. Aldman B, Gustafsson H, Nygren A, Johansson B, Jonasson H, Wersall J. The sound attenuation and the aerodynamically generated noise inside motorcycle helmets. 1981 International IRCOBI Conference on the Biomechanics of Impacts. Salon de Provence, France, September 8–10, 1981.
3. Aldman B, Thorngren L. The protective effect on crash helmets—a study of 96 motorcycle accidents. 1979 International IRCOBI Conference on the Biomechanics of Trauma. Goteborg, Sweden, September 5–7, 1979.
4. Aldman B, Thorngren L, Gustafsson H, Nygren A, Wersall J (1990) Motorcycle and moped accidents—study of the protective effect on crash helmets. International Motorcycle Safety Conference. Vol II. Washington DC.
5. Bishop PJ, Briard DB (1984) Impact performance of bicycle helmets. Can J Applied Sport Sci 9: 94–101.