CHERNIKOV , S. N.; CHERNIKOV , N. S. Complementability criterion of periodical almost soluble subgroups in the group containing it. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 44, n. 6, p. 822–826, 1992. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8016. Acesso em: 6 dec. 2025.