JOHANSEN, Soren. The Extremal Convex Functions. Mathematica Scandinavica, Berkeley, CA, United States, v. 34, p. 61–68, 1974. DOI: 10.7146/math.scand.a-11506. Disponível em: https://journals.msp.org/mscand/article/view/2141. Acesso em: 25 jul. 2026.