BUTZ, C.; MOERDIJK, I. A Definability Theorem for First Order Logic. BRICS Report Series, [S. l.], v. 4, n. 3, 1997. DOI: 10.7146/brics.v4i3.18782. Disponível em: https://tidsskrift.dk/brics/article/view/18782. Acesso em: 24 apr. 2024.