PACKER, J. A. Twisted group $C^*$-algebras corresponding to nilpotent discrete groups. MATHEMATICA SCANDINAVICA, [S. l.], v. 64, p. 109–122, 1989. DOI: 10.7146/math.scand.a-12250. Disponível em: https://www.mscand.dk/article/view/12250. Acesso em: 5 may. 2024.