MANUILOV, V.; THOMSEN, K. Extensions of $C^*$-algebras and translation invariant asymptotic homomorphisms. Mathematica Scandinavica, Berkeley, CA, United States, v. 100, n. 1, p. 131–160, 2007. DOI: 10.7146/math.scand.a-15018. Disponível em: https://journals.msp.org/mscand/article/view/679. Acesso em: 24 jul. 2026.