Lubis, R. H., Manullang, A. A., Malau, C. K., Pasaribu, M. D. S., & Situmorang, S. (2024). MEMBANGUN KETERAMPILAN ABAD 21: REVIEW LITERATUR TENTANG EFEKTIVITAS MODEL PEMBELAJARAN PROBLEM-BASED LEARNING (Building 21st Century Skills: A Literature Review on the Effectiveness of Problem-Based Learning Learning Models). Sindoro: Cendikia Pendidikan, 9(1), 11–20. https://doi.org/10.9644/sindoro.v9i1.7637