Miftakhi, D., and W. Ulfah. “Improving Achievement Motivation for Mentally Disabled Students at School for Exceptional Children (SLB) YPAC Pangkalpinang”. Berumpun: International Journal of Social, Politics, and Humanities, Vol. 2, no. 1, Mar. 2019, pp. 15-24, doi:10.33019/berumpun.v2i1.15.