Adam, Sutisno, and Sulmi Magfirah. “Implementation of Problem-Based Learning Model in TOEFL Preparation Program at Khairun University”. ELS Journal on Interdisciplinary Studies in Humanities 4, no. 4 (December 8, 2021): 424–430. Accessed February 5, 2025. http://journal.unhas.ac.id/index.php/jish/article/view/18611.