Fitriati Fitriati, Marlaini Marlaini, and Elizar Elizar. 2021. “Integrating Rich Task into the Mathematics Classroom to Develop Students’ Higher Order Thinking Skills: A Collaborative Action Research Study in a Secondary School”. Elementary Education Online 20 (1):479-94. https://ilkogretim-online.org/index.php/pub/article/view/2035.