1. Ball, D. (1990). Preservice elementary and secondary teachers’ understanding of division. Journal for Research in Mathematics Education, 21(2), 132–144.
2. Behr, M., Khoury, H., Harel, G., Post, T., & Lesh, R. (1997). Conceptual units analysis of preservice elementary school teachers’ strategies on a rational number as operator task. Journal for Research in Mathematics Education, 28(1), 48–69.
3. Behr, M. J., Lesh, R., Post, T. R., & Silver, E. A. (1983). Rational number concept. In R. Lesh & M. Landau (Eds.), Acquisitions of mathematics concepts and processes (pp. 91–126). New York: Academy Press.
4. Carpenter, T. P., Fennema, E., & Romberg, T. A. (1993). Rational numbers: An integration of research. Hillsdale: LEA.
5. Castro-Rodríguez, E., Rico, L., & Gómez, P. (2013, July). Meanings of fractions as demonstrated by future primary teachers in the initial phase of teacher education. Paper presented at the 12th ICME, Seoul, Korea.