1. Scott, D: On engendering an illusion of understanding, The Journal of Philosophy 68(1971), 787–807.
2. Quine, W.V.: Comments, in Boston Studies in the Philosophy of Science. D. Reidel Publishing Co., Dordrecht, 1963, pp. 97–104.
3. Scott, D: Advice on Modal Logic, in Philosophical Problems in Logic, edited by K. Lambert, D. Reidel Publ. Comp. 1970, pp. 143–173.
4. Weyl, H: The Ghost of Modality, in Philosophical Essays in memory of E. Husserl, edited by M. Farbes, Harvard Univ. Press, 1940, reprinted by Greenwood Press, New York, 1956.
5. Church, A: Introduction to mathematical logic, Vol. I, Princeton, N.J. 1968.