CHILDRESS, C. L.; CSORDAS, G. L. The Iversen theorem in a polydisc. Mathematica Scandinavica, Berkeley, CA, United States, v. 42, p. 64–70, 1978. DOI: 10.7146/math.scand.a-11737. Disponível em: https://journals.msp.org/mscand/article/view/1908. Acesso em: 25 jul. 2026.