Boichuk О. A.; ZHURAVLEV, V. F.; Pokutnyi О. О. Normally solvable operator equations in a Banach space. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 65, n. 2, p. 163–174, 2013. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2411. Acesso em: 5 dec. 2025.