SHEMETKOV, L. A. Complements and supplements to normal subgroups of finite groups. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 5, p. 678–689, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8340. Acesso em: 5 dec. 2025.