BECKHOFF, Ferdinand. Discrete group actions and the minimal primal ideal space. Mathematica Scandinavica, Berkeley, CA, United States, v. 80, p. 289–309, 1997. DOI: 10.7146/math.scand.a-12621. Disponível em: https://journals.msp.org/mscand/article/view/1008. Acesso em: 25 jul. 2026.