BROWN, L. G.; PEDERSEN, G. K. Approximation and convex decomposition by extremals in a $C^*$-algebra. MATHEMATICA SCANDINAVICA, [S. l.], v. 81, p. 69–85, 1997. DOI: 10.7146/math.scand.a-12866. Disponível em: https://www.mscand.dk/article/view/12866. Acesso em: 29 apr. 2024.