Risnawati, Risnawati, Arono Arono, and Wisma Yunita. “Problem-Based Learning (PBL): How Does It Affect the Speaking Skills of Introvert and Extrovert Students?”. Journal of Problem Based Learning in Higher Education 13, no. 1 (June 3, 2025): 184–200. Accessed February 18, 2026. https://journals.aau.dk/index.php/pbl/article/view/8596.