ARTEMOVICH, O. D. On I-Rigid and q-Rigid Rings. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 7, p. 989–993, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4878. Acesso em: 6 dec. 2025.