URBAŃSKI, M. Some remarks concerning modal propositional logic of questions. Logic and Logical Philosophy, [S. l.], v. 6, n. 6, p. 187–196, 1998. DOI: 10.12775/LLP.1998.010. Disponível em: https://apcz.umk.pl/LLP/article/view/LLP.1998.010. Acesso em: 17 jun. 2024.