1. Y. Bar-Hillel, ‘Rudolf Carnap, The Methodological Character of Theoretical Concepts’ (review), Journal of Sambolic Logic 25 (1960).
2. R. Carnap, ‘Testability and Meaning’, Philosophy of Science 3 and 4 (1936-1937).
3. R. Carnap, ‘The Methodological Character of Theoretical Concepts’, Minnesota Studies in the Philosophy of Science 1 (1956).
4. W. Craig, ‘Three Uses of the Herbrand-Gentzen Theorem in Relating ModelTheory and Proof-Theory’, Journal of Symbolic Logic 22 (1957).
5. H. Feigl, ‘Some Major Issues and Developments in the Philosophy of Science of Logical Empiricism’, Minnesota Studies in the Philosophy of Science 1 (1956).