NORGĖLA, Stanislovas. Resolution method for some class of formulas of modal logic S4. Lietuvos matematikos rinkinys, [S. l.], v. 44, n. spec., p. 521–524, 2004. DOI: 10.15388/LMR.2004.32028. Disponível em: https://www.journals.vu.lt/LMR/article/view/32028.. Acesso em: 30 jun. 2024.