Kullan, Saraswathy, Mahaliza Mansor, and Rosnah Ishak. “The Validity and Reliability of Sustainable Leadership Instrument”. International Journal of Academic Research in Progressive Education and Development 11, no. 1 (January 19, 2022). Accessed July 27, 2025. https://ijarped.com/index.php/journal/article/view/1894.