HENRARD, Guy. A fixed point theorem for $C^*$-crossed products with an Abelian group. Mathematica Scandinavica, Berkeley, CA, United States, v. 54, p. 27–39, 1984. DOI: 10.7146/math.scand.a-12038. Disponível em: https://journals.msp.org/mscand/article/view/1586. Acesso em: 25 jul. 2026.