Butarbutar, Ranta, Seli Marlina Radja Leba, Marnina ., and Angla Florensia Sauhenda. “Factors Associated With Speaking English As a Foreign Language Effectively in Higher Education”. KnE Social Sciences 8, no. 9 (May 26, 2023): 650–659. Accessed April 25, 2024. https://knepublishing.com/index.php/KnE-Social/article/view/13379.