López-Fernández, Iván, María Molina-Jodar, Francisco J. Garrido-González, Carlos A. Pascual-Martos, José L. Chinchilla, and Elvis A. Carnero. 2017. “Promoting Physical Activity at the School Playground: A Quasi-Experimental Intervention Study”. Journal of Human Sport and Exercise 11 (2):319-28. https://doi.org/10.14198/jhse.2016.112.05.