GALAZ-FONTES, F. Perturbating Upper Semi-fredholm With Strictly Singular Operators. Sarajevo Journal of Mathematics, [S. l.], v. 2, n. 1, p. 55–62, 2024. DOI: 10.5644/SJM.02.1.06. Disponível em: https://sjm.anubih.ba/index.php/sjm/article/view/428. Acesso em: 15 oct. 2024.