HEESWIJCK, Lutgarde Van. Duality in the theory of crossed products. Mathematica Scandinavica, Berkeley, CA, United States, v. 44, p. 313–329, 1979. DOI: 10.7146/math.scand.a-11813. Disponível em: https://journals.msp.org/mscand/article/view/1831. Acesso em: 25 jul. 2026.