FRIEDMAN, Yaakov; RUSSO, Bernard. Contracctive projections on operator triple systems. Mathematica Scandinavica, Berkeley, CA, United States, v. 52, p. 279–311, 1983. DOI: 10.7146/math.scand.a-12007. Disponível em: https://journals.msp.org/mscand/article/view/1612. Acesso em: 25 jul. 2026.