1. Ayer, A.J. 1936. Language, truth and logic. Repr. of the 2nd ed. (1946). New York: Dover, 1952.
2. ———. 1936/37. Verification and experience. Repr. in Ayer 1959, 228–243.
3. ———., ed. 1959. Logical positivism. New York: Free Press.
4. ———. 1982. The Vienna circle. Repr. in Ayer, A.J., Freedom and morality and other essays, Oxford: Clarendon Press, 1983, 159–177.
5. Carnap, R. 1927. Eigentliche und uneigentliche Begriffe. Symposion 1:355–374.