Meng, Chew Cheng, and Noraini Idris. “Assessment of Pre-Service Secondary Mathematics Teachers’ Van Hiele Levels of Geometric Thinking”.
Asian Journal of Assessment in Teaching and Learning, vol. 2, Dec. 2012, pp. 60-74,
https://ejournal.upsi.edu.my/index.php/AJATeL/article/view/1924.