1. Brown, M.: ‘Rules without reasons? Some evidence relating to the teaching of routine skills to low-attainers in mathematics’, International Journal of Mathematics Education in Science and Technology 13 (1982), 449–461.
2. Foxman, D. D. (ed.): Mathematical development, London 1980.
3. Hart, K. (ed.): Children’s understanding of mathematics: 11–16, London 1981.
4. Walther, G.: ‘Acquiring mathematical knowledge’, Mathematical Teaching, Nr. 101 (1982), 10–12.
5. Hutton, J.: ‘Memoirs of a math teacher 5. Logical reasoning’, Mathematics Teaching, Nr B1 (1977), 8–12