1. Ayer, A. J. (1936). Language, truth and logic. Victor Gollancz.
2. Ayer, A. J. (1946). Language, truth and logic (2nd ed.). Victor Gollancz.
3. Carnap, R. (1936). Testability and meaning (Part 1). Philosophy of Science, 3(4), 419–471.
4. Carnap, R. (1936b). Wahrheit und Bewährung. In Actes du Congrès international de philosophie scientifique, Sorbonne, Paris 1935, fasc. 4. Unité de la science, Hermann, 18–23. A modified version is translated as “Truth and Confirmation”, in Feigl and Sellars (1949) (pp. 119–127).
5. Carnap, R. (1937). Testability and meaning (Part 2). Philosophy of Science, 4(1), 1–40.