ELLIS, A. J. On Partial Orderings of Normed Spaces. Mathematica Scandinavica, Berkeley, CA, United States, v. 23, p. 123–132, 1968. DOI: 10.7146/math.scand.a-10903. Disponível em: https://journals.msp.org/mscand/article/view/2450. Acesso em: 25 jul. 2026.