AGHDAM, A.M.; KARIMI, F.; NAJAFIZADEH, A. ON THE SUBGROUPS OF TORSION-FREE GROUPS WHICH ARE SUBRINGS IN EVERY RING. Italian Journal of Pure and Applied Mathematics, [S. l.], v. 31, p. 63–76, 2013. Disponível em: https://journals.uniurb.it/index.php/ijpam/article/view/6160. Acesso em: 26 jul. 2026.