Castillo, Daniel, and Javier Raya-González. “Internal Load in Elite Young Soccer Players During a Whole Season According to Playing Positions”. International Journal of Physical Education, Fitness and Sports 7, no. 4 (December 30, 2018): 36–41. Accessed May 3, 2024. https://ijpefs.org/index.php/ijpefs/article/view/237.