References
- Brown, S. I., & Walter, M. I. (2005). The art of problem posing. Psychology Press.
- Freudenthal, H. (1973). Mathematics as an educational task. Reidel.
- Treffers, A. (1987). Three dimensions. A model of goal and theory description in mathematics education: The Wiskobas project. Kluwer Academic.
- Van den Heuvel-Panhuizen, M. (2000). Mathematics education in the Netherlands: A guided tour (pp. 1–32). Freudenthal Institute CD-rom for ICME9.