1. AyerA. J.: 1956, The Problem of Knowledge, Penguin, London.
2. Baxandall, P. R., Brown W. S., Rose, G. St. C., and Watson, F. R.: 1978, Proof in Mathematics (?If?, ?Then? and ?Perhaps?), Keele University.
3. BellA. W.: 1976, A study of pupils' proof-explanations in mathematical situations. Educational Studies in Mathematics 7, 23?40.
4. Bell, A. W.: 1978, ?The learning of process aspects of mathematics?, Proceedings of the 2nd Annual Conference of the International Group for the Psychology of Mathematics Education. pp. 48?78, Osnabruck.
5. Fischbein, E.: 1978, ?Intuition and mathematical education?, Proceedings of the 2nd Annual Conference of the International Group for the Psychology of Mathematics Education, pp. 148?176, Osnabruck.