WAHDE, Gösta. An Extremal Problem Related to Bernstein’s Approximation Problem. Mathematica Scandinavica, Berkeley, CA, United States, v. 15, p. 131–141, 1964. DOI: 10.7146/math.scand.a-10736. Disponível em: https://journals.msp.org/mscand/article/view/2611. Acesso em: 25 jul. 2026.