1. Acevedo Nistal, A., van Dooren, W., Clarebout, G., Elen, J. & Verschaffel, L. (2009). Conceptualising, investigating and stimulating representational flexibility in mathematical problem solving and learning: A critical review. ZDM The International Journal on Mathematics Education, 41(5), 627–636.
2. Ainsworth, S. (2006). A conceptual framework for considering learning with multiple representations. Learning and Instruction, 16, 183–198.
3. Arbuckle, J. L. (2012). IBM SPSS Amos 19 user’s guide. Chicago, IL: IBM.
4. Ball, D. L. (1993). Halves, pieces, and twoths: Constructing representational contexts in teaching fractions. In T. Carpenter, E. Fennema & T. Romberg (Eds.), Rational numbers: An integration of research (pp. 157–196). Hillsdale, NJ: Erlbaum.
5. Ball, D.L. & Hill, H.C. (2008). Mathematical knowledge for teaching (MKT) measures. Mathematics released items 2008. Retrieved from http://sitemaker.umich.edu/lmt/files/LMT_sample_items.pdf .