Prihatini, Fajar, Wikan Budi Utami, Fikri Aulia, and Fariz Fadila. “Problem Based Learning Assisted by Google Classroom on Conceptual Understanding Ability”. English Focus: Journal of English Language Education 5, no. 1 (December 3, 2021): 29-41. Accessed January 28, 2023. https://englishfocus.upstegal.ac.id/index.php/efj/article/view/121.