Khairi khalil, Jwan, and Ammar Mahmood. “On Left Slides (Upper or Lower) in E-Abacus Diagram”. Journal of Education and Science 32, no. 1 (March 1, 2023): 38–46. Accessed September 9, 2025. https://ojs.uomosul.edu.iq/index.php/edusj/article/view/42582.