ON CERTAIN SUB-SPACE OF X. Baghdad Science Journal, Iraq, Baghdad, v. 5, n. 4, p. 660–668, 2008. DOI: 10.21123/bsj.2008.5.4.660-668. Disponível em: https://bsj.uobaghdad.edu.iq/index.php/BSJ/article/view/947.. Acesso em: 19 may. 2024.