SHUNKOV, V. P. $T_0$-group and its place in the theory of groups. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 4, p. 572–576, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4643. Acesso em: 6 dec. 2025.