1. Behr, M., Harel, G., Post, T. and Lesh, R.: 1992, ‘Rational number, ratio, and proportion’, in D. Grouws (ed.), Handbook of Research on Mathematics Teaching and Learning, Macmillan, New York, pp. 296–333.
2. Carpenter, T.P., Ansell, E., Franke, M.L., Fennema, E. and Weisbeck, L.: 1993, ‘Models of problem solving: A study of kindergarten children's problem-solving processes’, Journal for Research in Mathematics Education 24(5), 427–440.
3. Charles, K. and Nason, R.: 2000, ‘Young children's partitioning strategies’, Educational Studies in Mathematics 43, 191–221.
4. Courant, R. and Robbins, H.: 1996, What is mathematics? 2nd ed., Oxford, New York.
5. Dienes, Z.P.: 1967, Fractions: An Operational Approach, Herder and Herder, New York.