Saad, Sukiman, et al. “Teaching Thinking Skills: Perception and Practice of in Teaching and Learning of Mathematics Teacher in the Classroom (18 - 36)”.
Jurnal Pendidikan Sains Dan Matematik Malaysia, vol. 2, no. 2, Apr. 2019, pp. 18-36,
https://ejournal.upsi.edu.my/index.php/JPSMM/article/view/1820.