ARSOV, A. Two cut-free modal sequent calculi. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 87, p. 165–177, 1995. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/411. Acesso em: 22 nov. 2024.