N. F. Kuzenny, S. S. Levishchenko, and N. N. . Semko, “On groups with invariant infinite non-Abelian subgroups”, Ukr. Mat. Zhurn., vol. 40, no. 3, pp. 314–321, Apr. 1988, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/9141