“Principal Transformational Leadership, School Culture, and Productivity of Medan Johor High School”, SNKP, vol. 2, hlm. 102–111, Jul 2024, Diakses: 26 Februari 2026. [Daring]. Tersedia pada: https://www.ejournal.ummuba.ac.id/index.php/SNKP/article/view/2149