Certification (2) Youth (2) Soccer players (2) Soccer (2) Motivation (Psychology) (2) Learning, Psychology of (2) Factor analysis (2) Etiquette (2) Content analysis (Communication) (2) Evidencia (2) Análisis de contenido (2) Análisis factorial (2) Certificación (2) Estudio (2) Motivación (2) Futbolistas (2) Fútbol (2) Etiqueta (2) Datos (2) Jóvenes (2) Aprendizaje (2) sport (2) course (2) Self-control (1) Psychology (1) Physical education and training (1) Perspective (1) Health (1) Blood--Sedimentation (1) Salud (1)