Katani, R. and Miccoli, M. M. (2001) “Upper Subrings of a Ring”, Ukrains’kyi Matematychnyi Zhurnal, 53(10), pp. 1427-1428. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4361 (Accessed: 15May2024).