GARDNER, B. J. A Note on Radicals and Polynomial Rings. Mathematica Scandinavica, Berkeley, CA, United States, v. 31, p. 83–88, 1972. DOI: 10.7146/math.scand.a-11414. Disponível em: https://journals.msp.org/mscand/article/view/2231. Acesso em: 25 jul. 2026.