FRIEDMAN, Y.; RUSSO, B. Contracctive projections on operator triple systems. MATHEMATICA SCANDINAVICA, [S. l.], v. 52, p. 279–311, 1983. DOI: 10.7146/math.scand.a-12007. Disponível em: https://www.mscand.dk/article/view/12007. Acesso em: 6 may. 2024.