EFFROS, Edward G.; STORMER, Erling. 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://tidsskrift.dk/math/article/view/11830. Acesso em: 14 aug. 2026.