ELLIOT, G. A.; TAKEMOTO, H. On $C^*$-algebra extensions relative to a factor of type $\mathrm{II}_\infty$. MATHEMATICA SCANDINAVICA, [S. l.], v. 53, p. 245–255, 1983. DOI: 10.7146/math.scand.a-12032. Disponível em: https://www.mscand.dk/article/view/12032. Acesso em: 7 may. 2024.