GOOTMAN, E. C.; OLESEN, D. Spectra of actions on type I $C^*$-algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 47, p. 329–350, 1980. DOI: 10.7146/math.scand.a-11894. Disponível em: https://www.mscand.dk/article/view/11894. Acesso em: 4 may. 2024.