KUZENNY , N. F.; LEVISHCHENKO , S. S.; SEMKO , N. N. On groups with invariant infinite non-Abelian subgroups. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 40, n. 3, p. 314–321, 1988. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/9141. Acesso em: 7 dec. 2025.