“Principal Transformational Leadership, School Culture, and Productivity of Medan Johor High School” (2024) PROSIDING SEMINAR NASIONAL KEGURUAN DAN PENDIDIKAN (SNKP), 2, hlm. 102–111. Tersedia pada: https://ejournal.ummuba.ac.id/index.php/SNKP/article/view/2149 (Diakses: 13 Januari 2026).