OSAMA AHMAD ALKATIB, M. Linear function in case of more than two sets. Journal of Education and Science, [S. l.], v. 23, n. 4, p. 157–169, 2010. DOI: 10.33899/edusj.2010.58462. Disponível em: https://ojs.uomosul.edu.iq/index.php/edusj/article/view/42501. Acesso em: 5 sep. 2025.