LIMAN, F. N. On periodical groups, where all decomposited $pd$-subgroups are normal . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 40, n. 1, p. 58–61, 1987. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/9055. Acesso em: 6 dec. 2025.