Hidayat, A., B. Tola, S. Sutanto, Saepudin, P. H. Halim, and S. Badruddin. “Productivity Lecturer in the Era of the Industrial Revolution 4.0: Confirmatory Factor Analysis (CFA)”. Helix - The Scientific Explorer | Peer Reviewed Bimonthly International Journal, vol. 9, no. 04, Aug. 2019, pp. 5102-7, https://helixscientific.pub/index.php/home/article/view/4.