LI, Jianghua; SHANGPING, Wang; XIAOQIN, Shen; XIAOQING, Sun. Quasi-unit regularity and $QB$-rings. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 64, n. 3, p. 415–425, 2012. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2586. Acesso em: 5 dec. 2025.