ROOHOLLAH, T.; HAMID, R. T.; MAHDI, S. Index of difficulty which is an effective factor on especial skill formation in basketball free throw: index of learning difficulty hypothesis. Physical Education of Students, [S. l.], v. 22, n. 2, p. 83–90, 2018. DOI: 10.15561/20755279.2018.0205. Disponível em: https://sportedu.org.ua/index.php/PES/article/view/581. Acesso em: 24 jul. 2026.