1. Björklund, C., van den Heuvel-Panhuizen, M., & Kullberg, A. (2020). Research on early childhood mathematics teaching and learning. ZDM, 52, 607–619.
2. Creswell, W. J., & Poth, N. C. (2018). Qualitative inquiry and research design: Choosing among five approaches (4th ed.). Sage Publications.
3. Giroux, H. A. (1989). Schooling for democracy: Critical pedagogy in the modern age. Routledge.
4. Kubo, R. (2017). Democratic ability and critical thinking in mathematics education. In Proceedings of the 5th Spring Conference of the Japanese Society for Mathematics Education (pp. 201–208). The Japanese Society for Mathematics Education (in Japanese).
5. Matsuo, N., & Nakawa, N. (2019). Preschool children’s understanding of length and area measurement in Japan. In U. T. Jankvist, M. van den Heuvel-Panhuizen, & M. Veldhuis (Eds.), Proceedings of the Eleventh Congress of the European Society for Research in Mathematics Education (pp. 2311–2319). Freudenthal Group & Freudenthal Institute, Utrecht University, Netherlands and ERME.