Siburian P, Pasaribu A, Manullang J. Model Development of Managerial Supervision for the Elementary School Principal in Medan Indonesia. IJSBAR [Internet]. 2016 Nov. 26 [cited 2024 May 10];30(4):1-10. Available from: https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/6488