Nainggolan, Tioria, and Sutikno. “Development of Collaborative Learning to Improve Student’s Writing Skills Class X SMA Negeri 1 Dolok Merawan Academic Year 2022-2023”. International Journal of Social Sciences and Humanities Invention 10, no. 03 (March 21, 2023): 7805–7809. Accessed May 30, 2024. https://valleyinternational.net/index.php/theijsshi/article/view/3888.