TushevA. V. “On Solvable Groups With Proper Quotient Groups of Finite Rank”. Ukrains’kyi Matematychnyi Zhurnal 54, no. 11 (November 25, 2002): 1560-1568. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4192.