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References
Ruth Barcan Marcus
Possibiha and possible worlds![Open Access Link](images/OAlink.png)
1985
Grazer Philosophische Studien 25
![Open Access Link](images/OAlink.png)
Modal logic, modal semantics and their applications![Open Access Link](images/OAlink.png)
1981
in: Philosophie du langage, logique philosophique / Philosophy of language, philosophical logic, Dordrecht : Springer
![Open Access Link](images/OAlink.png)