AHMED KHALEL, L.; JASIM MOHAMMED, A. Kinds of crossed modules. Journal of Education and Science, [S. l.], v. 22, n. 2, p. 354–369, 2009. DOI: 10.33899/edusj.2009.57689. Disponível em: https://edusj.uomosul.edu.iq/index.php/edusj/article/view/41625. Acesso em: 10 sep. 2025.