Syarif, M., and M. S. Moenada. “Boarding School (Pesantren) Education During Covid-19 Pandemic at Dar El Hikmah Pekanbaru Indonesia”. Khalifa: Journal of Islamic Education, vol. 4, no. 2, Aug. 2020, pp. 161-74, doi:10.24036/kjie.v4i2.54.