MUNCH, Niels Juul. Relatively ’closable’ states on $C^*$-algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 57, p. 236–248, 1985. DOI: 10.7146/math.scand.a-12115. Disponível em: https://journals.msp.org/mscand/article/view/1551. Acesso em: 25 jul. 2026.