ON G-OPEN SET. Baghdad Science Journal, Iraq, Baghdad, v. 4, n. 3, p. 482–484, 2021. DOI: 10.21123/bsj.2007.4.3.482-484. Disponível em: https://bsj.uobaghdad.edu.iq/index.php/BSJ/article/view/828.. Acesso em: 12 may. 2024.