Waruwu, Marinus, Aan Komariah, Udin Syaefudin Saud, and Endang Herawan. 2020. “On The Job Skill-Based Servant Leadership Training Model for Principal Effectiveness”. International Journal of Psychosocial Rehabilitation 24 (5): 3270-79. https://doi.org/10.61841/pxz65q55.