JENSEN, A. Some Results Concerning a General Set Theoretical Approach to Logic. MATHEMATICA SCANDINAVICA, [S. l.], v. 16, p. 5–24, 1965. DOI: 10.7146/math.scand.a-10742. Disponível em: https://www.mscand.dk/article/view/10742. Acesso em: 4 may. 2024.