OLSHANSKY , A. Yu. Nesting of periodical groups into simple periodica groups. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 44, n. 6, p. 845–847, 1992. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8021. Acesso em: 5 dec. 2025.