MORALES PARRA, S.; SAMPER, C. Difficulties in learning the formal deductive demonstration in euclidean geometry. Amazonia Investiga, [S. l.], v. 4, n. 6, p. 55–68, 2015. Disponível em: https://mail.amazoniainvestiga.info/index.php/amazonia/article/view/685. Acesso em: 20 jan. 2026.