KLEIN, A. A.; BELL, Howard E. Some Noteworthy Properties of Zero Divisors in Infinite Rings. MATHEMATICA SCANDINAVICA, [S. l.], v. 75, p. 59–66, 1994. DOI: 10.7146/math.scand.a-12502. Disponível em: https://tidsskrift.dk/math/article/view/12502. Acesso em: 14 aug. 2026.