1. Robert M. Adams, ?Theories of actuality?, Noûs 8 (1974): 211?231.
2. Phillip Bricker, Worlds and Propositions: The Structure and Ontology of Logical Space (doctoral dissertation, Princeton University, 1983).
3. Rudolf Carnap, Meaning and Necessity: A Study in Semantics and Modal Logic, 2nd ed. (Chicago: The University of Chicago Press, 1956).
4. Rudolf Carnap, Logical Foundations of Probability (Chicago: University of Chicago Press, 1950).
5. M. A. Dickmann, Large Infinitary Languages: Model Theory (Amsterdam: North-Holland Publishing Corp., 1975).