DYRE, J. C. Non-standard characterisations of ideals in $C(X)$. MATHEMATICA SCANDINAVICA, [S. l.], v. 50, p. 44–54, 1982. DOI: 10.7146/math.scand.a-11942. Disponível em: https://www.mscand.dk/article/view/11942. Acesso em: 6 may. 2024.