Kuzenny NF, Levishchenko SS, Semko NN. On groups with invariant infinite non-Abelian subgroups. Ukr. Mat. Zhurn. [Internet]. 1988 Apr. 28 [cited 2025 Dec. 7];40(3):314-21. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/9141