2Graeme S Halford, Children's Understanding: the Development of Mental Models, LEA publishers, 1993.
3Robert J, Sternberg, The Nature of Mathematics Thinking, LEA publishers, 1996.
4Douglas P Newton ,Teaching for Understanding - What it is and How to do it?, Routledge Falmer, 2000.
5L J Rips, A Companion Guide to Cognitive Science, Malden ,MA: Blackwell, 1998.
6H Gentner, Frames of Mind, London: Fontana Publishers, 1993.
7J G Greeno, Situation mantal models and generative knowledge,Harvard University Press, 1988.
8National Council of Teachers of Mathematics, Principles and Standards for school mathematics 2000.
9Stephen J Pape, Mourat A, Tchoshanov, The Role of Representations in Developing Mathematical Understanding, in: Theory into Practice, Volume 40, 2001.