RASHID, M. M. Property $(w)$ of upper triangular operator Matrices. Tamkang Journal of Mathematics, [S. l.], v. 51, n. 2, p. 81-99, 2020. DOI: 10.5556/j.tkjm.51.2020.2256. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/2256. Acesso em: 21 oct. 2020.