DE, Glovanni F.; SYSAK, Ya. P.; FRANCLOSI, S. On ascending and subnormal subgroups of infinite factorized groups. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 6, p. 842–848, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5070. Acesso em: 5 dec. 2025.