Purwasih, Ratih, and Rahimmulaily Rahimmulaily. “Analysis of Difficulty Level of Information System Students in Communicating English in Industrial Era 4.0”. Jurnal Pendidikan Vokasi 9, no. 1 (March 11, 2019): 83–91. Accessed May 5, 2025. https://journal.uny.ac.id/index.php/jpv/article/view/22761.