EFFROS, Edward G.; STORMER, Erling. Positive projections and Jordan structure in operator algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 45, p. 127–138, 1979. DOI: 10.7146/math.scand.a-11830. Disponível em: https://journals.msp.org/mscand/article/view/1819. Acesso em: 25 jul. 2026.