López-Fernández, I.; Molina-Jodar, M.; Garrido-González, F. J.; Pascual-Martos, C. A.; Chinchilla, J. L.; Carnero, E. A. Promoting Physical Activity at the School Playground: A Quasi-Experimental Intervention Study. J. Hum. Sport Exerc. 2017, 11, 319-328.