Wahid, K., M. S. A. M. Nawawi, and M. Z. Zainuddin. “Study on Sky Brightness and Length of Shadow To Determine The Early Time of Dhuha Prayer”. Asian Journal of Applied Sciences, vol. 3, no. 2, Apr. 2015, https://www.ajouronline.com/index.php/AJAS/article/view/2536.