WAHDE, Gösta. An Extremal Problem Related to the Theory of Quasi-Analytic Functions. Mathematica Scandinavica, Berkeley, CA, United States, v. 7, p. 126–132, 1959. DOI: 10.7146/math.scand.a-10566. Disponível em: https://journals.msp.org/mscand/article/view/2774. Acesso em: 8 sep. 2026.