NG, Kung-fu. On a Computation Rule for Polars. Mathematica Scandinavica, Berkeley, CA, United States, v. 26, p. 14–16, 1970. DOI: 10.7146/math.scand.a-10962. Disponível em: https://journals.msp.org/mscand/article/view/2362. Acesso em: 25 jul. 2026.