OLSEN, Catherine L.; PEDERSEN, Gert K. Corona $C^*$-algebras and their applications to lifting problems. MATHEMATICA SCANDINAVICA, [S. l.], v. 64, p. 63–86, 1989. DOI: 10.7146/math.scand.a-12248. Disponível em: https://tidsskrift.dk/math/article/view/12248. Acesso em: 13 aug. 2026.