PIETRUSZCZAK, A. Simplified Kripke style semantics for some very weak modal logics. Logic and Logical Philosophy, [S. l.], v. 18, n. 3-4, p. 271–296, 2010. DOI: 10.12775/LLP.2009.013. Disponível em: https://apcz.umk.pl/LLP/article/view/LLP.2009.013. Acesso em: 21 feb. 2024.