LORING, Terry A. Projective $C^*$-algebras. Mathematica Scandinavica, Berkeley, CA, United States, v. 73, p. 274–280, 1993. DOI: 10.7146/math.scand.a-12471. Disponível em: https://journals.msp.org/mscand/article/view/1195. Acesso em: 24 jul. 2026.