ELLIS, A. J. Some Applications of Convexity Theory to Banach Algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 33, p. 23–30, 1973. DOI: 10.7146/math.scand.a-11468. Disponível em: https://tidsskrift.dk/math/article/view/11468. Acesso em: 14 aug. 2026.