KATAYAMA, Y. Remarks on a $C^*$-dynamical system. MATHEMATICA SCANDINAVICA, [S. l.], v. 49, p. 250–258, 1981. DOI: 10.7146/math.scand.a-11934. Disponível em: https://www.mscand.dk/article/view/11934. Acesso em: 4 may. 2024.