A Riyanto, M L Nurfachsya, and G Sianturi. “Employee Productivity Model at Mineral, Coal and Geothermal Resources Center”. Proceeding of International Conference on Business, Economics, Social Sciences, and Humanities 5 (March 10, 2023): 157–163. Accessed June 4, 2025. https://proceedings.unikom.ac.id/index.php/icobest/article/view/130.