Arnal-Palacián, Mónica, Nuria Begué, and Cristina Blanco. “The Impact of Sending Letters in Improving Teaching-Learning Process of Natural Number of Pre-Service Teachers”. Journal of Honai Math 5, no. 1 (March 13, 2022): 61–74. Accessed October 12, 2026. https://journalfkipunipa.org/index.php/jhm/article/view/240.