ZIZLER, V. On Some Extremal Problems in Banach Spaces. MATHEMATICA SCANDINAVICA, [S. l.], v. 32, p. 214–224, 1973. DOI: 10.7146/math.scand.a-11456. Disponível em: https://www.mscand.dk/article/view/11456. Acesso em: 20 apr. 2024.