Acuña Delgado, Ángel, and Guillermo Acuña Gómez. “Physical Training in the Environment: Origin, Evolution and Reinterpretation Modern Times”. Journal of Human Sport and Exercise 11, no. 1 (December 25, 2016): 89–98. Accessed April 18, 2024. https://www.jhse.ua.es/article/view/2016-v11-n1-physical-training-environment-origin-evolution-reint.