Siagian, Pargaulan. “Article of KDBK in English 20 The Advancement of Demographics Learning Tools: The Advancement of Demographics Learning Tools”. Advances in Social Sciences Research Journal 7, no. 3 (April 4, 2020): 279–295. Accessed April 25, 2024. https://journals.scholarpublishing.org/index.php/ASSRJ/article/view/7936.