Rahayuningsih, S., S. Sirajuddin, and N. Nasrun. “Cognitive Flexibility: Exploring students’ Problem-Solving in Elementary School Mathematics Learning”. JRAMathEdu (Journal of Research and Advances in Mathematics Education), vol. 6, no. 1, Dec. 2020, pp. 59-70, doi:10.23917/jramathedu.v6i1.11630.