1. Lakatos, I. (1970). Falsification and the methodology of scientific research programmes. In I. Lakatos & A. Musgrave (Eds.), Criticism and the growth of knowledge (pp. 91-196). Cambridge, England: Cambridge University Press.
2. Popper, K. (1959). The logic of scientific discovery. London: Hutchinson.
3. Quine, W. V. O. (1953). Two dogmas of empiricism. In W. V. O. Quine (Ed.), From a logical point of view (pp. 20-46). Cambridge, MA: Harvard University Press.
4. Wittgenstein, L. (1969). G. E. M. Anscombe & G. H. von Wright (Eds) and D. Paul & G. E. M. Anscombe (Trans.). On certainty. Oxford: Blackwell.