González-Giraldo, O. E.; Castellanos Sánchez, M. T. The Abacus Closed As a Pedagogical Mediation in the Construction of Multiplication and Division Operations in the Third Degree of Official Educational Institutions. IyD 2019, 6 (2), 98-108. https://doi.org/10.26620/uniminuto.inclusion.6.2.2019.98-108.