Soriano-Férriz, Beatriz, and Fernando Alacid. 2018. “FLEXIBILITY PROGRAMS AND EXERCISES WITHIN PHYSICAL EDUCATION CLASSES, IN SCHOOLCHILDREN, AND THEIR EFFECT ON THE IMPROVEMENT OF HAMSTRING EXTENSIBILITY: A SYSTEMATIC REVIEW”. MHSalud: Revista En Ciencias Del Movimiento Humano Y Salud 15 (1): 1-11. https://doi.org/10.15359/mhs.15-1.1.