“The Influence of Competency and Leadership Style on the Performance of Educational Personnel at HKBP Nommensen University Medan”. Proceeding of International Conference on Pesantren (ICOP) 2, no. 1 (August 21, 2025). Accessed September 15, 2026. https://ejournal.darunnajah.ac.id/index.php/icop/article/view/586.