Aghdam, A., Karimi, F. and Najafizadeh, A. (2013) “ON THE SUBGROUPS OF TORSION-FREE GROUPS WHICH ARE SUBRINGS IN EVERY RING”, Italian Journal of Pure and Applied Mathematics, 31, pp. 63–76. Available at: https://journals.uniurb.it/index.php/ijpam/article/view/6160 (Accessed: 26 July 2026).