Weiss, M. R., & Wiese-Bjornstal, D. M. (2009). Promoting positive youth development through physical activity. Retrieved from http://presidentschallenge.org...
Zarrett, N., Lerner, R. M., Carrano, J., Fay, K., Peltz, J. S., Li, Y. (2008). Variations in adolescent engagement in sports and its influence...