H. SHUKER, N.; Q. MOHAMMAD, H.; H. AHMAD, S. On Singular and non Singular Rings. AL-Rafidain Journal of Computer Sciences and Mathematics, [S. l.], v. 3, n. 1, p. 111–116, 2006. DOI: 10.33899/csmj.2006.164040 . Disponível em: https://csmj.uomosul.edu.iq/index.php/csmj/article/view/37084. Acesso em: 18 dec. 2025.