SKOUMPOURDI, Chrysanthi. Designing a ’modern’ abacus for early childhood mathematics. Teaching Mathematics and Computer Science, [S. l.], v. 7, n. 2, p. 187–199, 2009. DOI: 10.5485/TMCS.2009.0220. Disponível em: https://ojs.lib.unideb.hu/tmcs/article/view/14854. Acesso em: 27 sep. 2024.