Segura Castro, Diego, et al. “SELF-EFFICACY, PRECOMPETITIVE ANXIETY AND SELF-PERCEPTION OF PERFORMANCE IN UNDER 17 AND JUVENILE SOCCER PLAYERS”. MHSalud: Revista En Ciencias Del Movimiento Humano Y Salud, vol. 15, no. 2, Aug. 2018, pp. 1-15, https://doi.org/10.15359/mhs.15-2.3.