Gale Group, Booth, D., & Thorpe, H. (2007). Berkshire encyclopedia of extreme sports. Berkshire Publishing Group.
Chicago Style aipamenaGale Group, Douglas Booth, and Holly Thorpe. Berkshire Encyclopedia of Extreme Sports. Great Barrington, Mass: Berkshire Publishing Group, 2007.
MLA aipamenaGale Group, et al. Berkshire Encyclopedia of Extreme Sports. Berkshire Publishing Group, 2007.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.