PREDICTING PERFORMANCE OF FRONTLINER: ASSESSING THE ROLES OF MOTIVATION, WORK DISCIPLINE, ENVIRONMENT PT KERETA API PARIWISATA DAOP VI YOGYAKARTA. jopt. 2026;23(1):1-16. Diakses Oktober 3, 2026. https://jurnal.stieieu.ac.id/index.php/opt/article/view/191