PISKUN, M. M.; SEMKO, N. N. On the application of some concepts of ring theory to the study of the influence of systems of subgroups of a group. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 60, n. 5, p. 657–668, 2008. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3184. Acesso em: 7 apr. 2025.