Muhammad Dawamul Mughni, and Putri Aisyiyah Rakhma Devi. “Implementation Of Teacher Presence System Using Mobile-Based Geofencing &Amp; Haversine Formula Methods”. Applied Technology and Computing Science Journal 6, no. 1 (June 30, 2023): 31–40. Accessed July 3, 2024. https://journal2.unusa.ac.id/index.php/ATCSJ/article/view/4119.