1. Bassey, M. (1990). On the nature of research in education. Research Intelligence.
2. Barrett, J. E., Clements, D. H. & Sarama, J. (Eds.). (2017). Children's measurement: A longitudinal study of children's knowledge and learning of length, area, and volume. Journal for Research in Mathematics Education Monograph Series, Vol. 16, Reston, VA: National Council of Teachers of Mathematics.
3. A combined application of APOS and OSA to explore undergraduate students’ understanding of polar coordinates
4. Corberán, R. (1996). Análisis del concepto de área de superficies planas. Estudio de su comprensión por los estudiantes desde primaria a la universidad. [Doctoral dissertation, University of Valencia]. https://www.uv.es/aprengeom/archivos2/Corberan96.pdf