1. National Police Agency of Japan. Status of traffic accident in 2016 (in Japanese). Available at: https://www.e-stat.go.jp/stat-search/file-download?statInfId=000031559551&fileKind=2
2. Japanese Industrial Standards Committee. Protective helmets for bicycle users (in Japanese). JIS. T8134:2018; 2018.
3. United States Consumer Product Safety Commission. Safety Standard for Bicycle Helmets Final Rule (16 CFR Part 1203); 1998. Avauilable at: https://www.govinfo.gov/content/pkg/CFR-2012-title16-vol2/pdf/CFR-2012-title16-vol2-part1203.pdf
4. British Standards Institution (BSI). BS EN 1078:2012 + A1:2012. Helmets for pedal cyclists and for users of skateboards and roller skates; 2012.
5. Standards Australia. AS/NZS 2512.3.1 Methods of testing protective helmets—determination of impact energy attenuation—helmet drop test; 2007.