Marsidi, Dafik, Susanto, and Arika Indah Kristiana. “The Development of RBL-STEM Learning Materials to Improve Students’ Combinatorial Thinking Skills in Solving DNA Protection Problems”. International Journal of Instruction 18, no. 3 (July 2, 2025): 409–434. Accessed July 3, 2025. https://e-iji.net/ats/index.php/pub/article/view/783.