1. M. GERSON “Some undecidable modal extensions of classical propositional calculus.”
2. “Some embedding theorems for modal logic.”;DAVID;Notre Dame Journal of formal logic,1971
3. “Semantic analysis of tense logics.”;THOMASON;The journal of symbolic logic,1972
4. “Reduction of tense logic to modal logic, I.”;THOMASON;The journal of symbolic logic,1974
5. “Reduction of second-order logic to modal logic.”;THOMASON;Zeitschrift für mathematische Logik und Grundlagen der Mathematik,1975