KLEIN, A. A.; BELL, Howard E. Some Noteworthy Properties of Zero Divisors in Infinite Rings. Mathematica Scandinavica, Berkeley, CA, United States, v. 75, p. 59–66, 1994. DOI: 10.7146/math.scand.a-12502. Disponível em: https://journals.msp.org/mscand/article/view/1174. Acesso em: 24 jul. 2026.