Columbia subject headings:
Carnap, Rudolf, 1891-1970--Criticism and interpretation.
Hempel, Carl G. (Carl Gustav), 1905-1997--Criticism and interpretation.
Logic, Symbolic and mathematical.
Semantics (Philosophy)
Harvard subject headings:
Carnap, Rudolf, 1891-1970--Criticism and interpretation.
Hempel, Carl G. (Carl Gustav), 1905-1997--Criticism and interpretation.
Logic, Symbolic and mathematical.
Princeton subject headings:
Carnap, Rudolf, 1891-1970.
Concepts.
Hempel, Carl G. (Carl Gustav), 1905-1997.