OLESEN, D. A classification of ideals in crossed products. MATHEMATICA SCANDINAVICA, [S. l.], v. 45, p. 157–167, 1979. DOI: 10.7146/math.scand.a-11833. Disponível em: https://www.mscand.dk/article/view/11833. Acesso em: 4 may. 2024.