Febriawan, M. R., and S. A. Pangestu. “Thabit Ibn Qurra : History and The Influence to Detemine The Time of Praying Fardhu”. Proceeding International Conference on Science and Engineering, vol. 4, Feb. 2021, pp. 255-8, http://sunankalijaga.org/prosiding/index.php/icse/article/view/667.