ELLIS, A. J. Some Applications of Convexity Theory to Banach Algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 33, p. 23–30, 1973. DOI: 10.7146/math.scand.a-11468. Disponível em: https://journals.msp.org/mscand/article/view/2199. Acesso em: 25 jul. 2026.