Cass-Zubiria, M. M., D. C. Morales Rosales, and P. J. Mayoral Valdivia. “Study of the Use of Tangible-Ludic Materials in Elementary School”. CIEX Journ@l, Vol. 12, no. 12, Apr. 2021, pp. 51-69, http://ciex.edu.mx/journalv2/index.php/CJ/article/view/193.