Incidence, clinical course, and predictors of prolonged recovery time following sport-related concussion in high school and college athletes - McCrea, M; Guskiewicz, K; Randolph, C; Barr, W B; Hammeke, T A; Marshall, S W; Powell, M R; Woo Ahn, K; Wang, Y; Kelly, J P (J Int Neuropsychol Soc, 2013)