Columbia subject headings:
Logic, Symbolic and mathematical.
Modality (Logic)
Ontology.
Possibility.
Semantics (Philosophy)
Harvard subject headings:
Logic, Symbolic and mathematical.
Metaphysics
Modality (Logic)
Ontology.
Possibility.
Semantics (Philosophy)
Princeton subject headings:
Logic, Symbolic and mathematical.
Modality (Logic)
Ontology.
Possibility.
Semantics (Philosophy)