“PREDICTING PERFORMANCE OF FRONTLINER: ASSESSING THE ROLES OF MOTIVATION, WORK DISCIPLINE, ENVIRONMENT PT KERETA API PARIWISATA DAOP VI YOGYAKARTA”, jopt, vol. 23, no. 1, hlm. 1–16, Jul 2026, Diakses: Okt 03, 2026. Tersedia pada: https://jurnal.stieieu.ac.id/index.php/opt/article/view/191