Simbolon, Rinci, and Saraswati Silalahi. “The Effectiveness of Project-Based Learning on 21st-Century Skills in Elementary Schools: A Literature Review”. BASICA 5, no. 2 (July 17, 2026): 187–204. Accessed October 7, 2026. https://ejournal.insuriponorogo.ac.id/index.php/basica/article/view/10291.