Tylyshchak, A. A. “On the Maximal Unipotent Subgroups of a Special Linear Group over Commutative Ring”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 8 (August 25, 2019): 1150–1156. Accessed April 14, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/1506.