BECKHOFF, F. Discrete group actions and the minimal primal ideal space. MATHEMATICA SCANDINAVICA, [S. l.], v. 80, p. 289–309, 1997. DOI: 10.7146/math.scand.a-12621. Disponível em: https://www.mscand.dk/article/view/12621. Acesso em: 3 may. 2024.