Mutmainah, Siti, and Mega Suliani. “An Ethnographic Study of Abacus Use Among Visually Impaired Individuals in Solving Addition and Subtraction Problems”. Jurnal Pendidikan Matematika Universitas Lampung 14, no. 2 (June 29, 2026): 147–156. Accessed July 17, 2026. https://jurnal.pbs.fkip.unila.ac.id/index.php/jpm/article/view/1522.