Utami, Y. and Ade Andriani 2023. Analysis of Students’ Difficulties in Solving Mathematics Problems Based on High Order Thinking Skill (HOTS) Based on Polya Heuristic Stages at SMP Negeri 15 Medan. Formosa Journal of Multidisciplinary Research. 2, 1 (Jan. 2023), 191–206. DOI:https://doi.org/10.55927/fjmr.v2i1.2348.