J. Serrano, R. Reis, T. Fonseca, R. Paulo, S. Honório, and M. Batista, “Pre-Competitive Anxiety: A comparative study between ‘Under 12’ and Senior teams in football (Ansiedad Pre-Competitiva: Estudio comparativo entre equipos de fútbol infantil y fútbol senior)”, Retos, vol. 36, pp. 318–326, Jul. 2019, doi: 10.47197/retos.v36i36.67129.