Rahmat, C. M. . Zubainur, and Marwan. “Students’ Mathematical Problem Solving Abilities Through Realistic Mathematics Educational Approach in Elementary Schools”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 54, no. 1, Sept. 2020, pp. 138-45, https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/9766.