NORGĖLA, Stasys. Some decidable classes of modal logic S5. Lietuvos matematikos rinkinys, [S. l.], v. 39, n. III, p. 322–325, 1999. DOI: 10.15388/LMD.1999.35643. Disponível em: https://www.journals.vu.lt/LMR/article/view/35643.. Acesso em: 11 sep. 2024.