EFFROS, E. G.; STORMER, E. Positive projections and Jordan structure in operator algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 45, p. 127–138, 1979. DOI: 10.7146/math.scand.a-11830. Disponível em: https://www.mscand.dk/article/view/11830. Acesso em: 3 jul. 2024.