Dashkova, O. Yu. “Hypercentral Groups of Finite Subnormal Rank”. Ukrains’kyi Matematychnyi Zhurnal 47, no. 11 (November 25, 1995): 1577–1580. Accessed February 17, 2026. https://umj.imath.kiev.ua/index.php/umj/article/view/5550.