“Improving Achievement Motivation for Mentally Disabled Students at School for Exceptional Children (SLB) YPAC Pangkalpinang”. Berumpun: International Journal of Social, Politics, and Humanities 2, no. 1 (Maret 29, 2019): 15–24. Diakses April 29, 2026. https://berumpun.ubb.ac.id/index.php/BRP/article/view/8.