Williford, H. N., Kirkpatrick, J., Scharff-Olson, M., Blessing, D. L., & Wang, N. Z. (1994). Physical and performance characteristics of successful high school football players. The American journal of sports medicine, 22(6), S. 859-862.

Williford, Henry N., Jane Kirkpatrick, Michele Scharff-Olson, Daniel L. Blessing, and Nai Zhen Wang. "Physical and Performance Characteristics of Successful High School Football Players." The American Journal of Sports Medicine 22, no. 6 (1994): S. 859-862.

Williford, Henry N., et al. "Physical and Performance Characteristics of Successful High School Football Players." The American Journal of Sports Medicine 22.6 (1994): S. 859-862.