JOHANSEN, Soren. The Extremal Convex Functions. MATHEMATICA SCANDINAVICA, [S. l.], v. 34, p. 61–68, 1974. DOI: 10.7146/math.scand.a-11506. Disponível em: https://tidsskrift.dk/math/article/view/11506. Acesso em: 13 aug. 2026.