Sapta A, Pakpahan SP, Sirait S. Using The Problem Posing Learning Model Based On Open Ended To Improve Mathematical Critical Thinking Ability. J. of Research in Math. Trends and Tech. [Internet]. 2019Mar.7 [cited 2024Nov.23];1(1):12-5. Available from: https://talenta.usu.ac.id/jormtt/article/view/752