SUDO, Takahiro. Real rank estimate by hereditary $C^*$-subalgebras by projections. Mathematica Scandinavica, Berkeley, CA, United States, v. 100, n. 2, p. 361–367, 2007. DOI: 10.7146/math.scand.a-15027. Disponível em: https://journals.msp.org/mscand/article/view/670. Acesso em: 24 jul. 2026.