Siburian, P., Pasaribu, A. and Manullang, J. (2016) “Model Development of Managerial Supervision for the Elementary School Principal in Medan Indonesia”, International Journal of Sciences: Basic and Applied Research (IJSBAR), 30(4), pp. 1–10. Available at: https://gssrr.org/JournalOfBasicAndApplied/article/view/6488 (Accessed: 17 September 2025).