Li, Jianghua, Wang Shangping, Shen Xiaoqin, and Sun Xiaoqing. “Quasi-Unit Regularity and $QB$-Rings”. Ukrains’kyi Matematychnyi Zhurnal 64, no. 3 (March 25, 2012): 415-425. Accessed April 19, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2586.