Zaitsev О. I.; MAZNICHENKO, V. A. On hypercentral expansions of the Abelian Groups. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 40, n. 5, p. 632–635, 1988. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8813. Acesso em: 6 dec. 2025.