Prien, A., Grafe, A., Rössler, R., Junge, A., & Verhagen, E. (2018). Epidemiology of Head Injuries Focusing on Concussions in Team Contact Sports: A Systematic Review. Sports Medicine (Auckland, N.Z.). https://doi.org/10.1007/s40279-017-0854-4 (Original work published 2018)