BLACKADAR, Bruce. The Homotopy Lifting Theorem for Semiprojective $C^*$-Algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 118, n. 2, p. 291–302, 2016. DOI: 10.7146/math.scand.a-23691. Disponível em: https://journals.msp.org/mscand/article/view/354. Acesso em: 24 jul. 2026.