Sousa, Honorato José, et al. “El Efecto De Los Partidos Reducidos De Fútbol Equilibrados Y Desequilibrados Em La calificación Del Esfuerzo Percebido Em Los Jugadores Juveniles (The Effect of Balanced and Unbalanced Soccer Small-Sided Games on the Rating of Perceived Exertion in Youth”. Retos, vol. 41, July 2021, pp. 440-6, https://doi.org/10.47197/retos.v0i41.83091.