1. Intuitionistic modal logic with quantifiers;Fitch;Portugaliae Mathematicae,1948
2. On the semantic non-completeness of certain Lewis calculi;Halldén;Journal of Symbolic Logic,1951
3. Results concerning the decision problem of Lewis's calculi S3 and S6;Halldén;Journal of Symbolic Logic,1949
4. An Introduction to Modal Logic;Hughes,1968
5. A survey of some connections between classical, intuitionistic and minimal logic;Prawitz,1968