Quasi-posinormal operators. Baghdad Science Journal, Iraq, Baghdad, v. 7, n. 3, p. 1282–1287, 2010. DOI: 10.21123/bsj.2010.7.3.1282-1287. Disponível em: https://bsj.uobaghdad.edu.iq/index.php/BSJ/article/view/1102.. Acesso em: 2 may. 2024.