Simanjuntak, Junihot. “The Impact of Principal Leadership on The Effectiveness of Learning in Christian Senior High School in Bandung, Indonesia”. Kelola: Jurnal Manajemen Pendidikan 8, no. 1 (June 22, 2021): 11-21. Accessed October 23, 2021. https://ejournal.uksw.edu/kelola/article/view/4514.