Lusyana, Evvy, and Wahyu Setyaningrum. “Van Hiele Instructional Package for Vocational School Students’ Spatial Reasoning”. Beta: Jurnal Tadris Matematika 11, no. 1 (May 31, 2018): 79-100. Accessed November 12, 2019. https://jurnalbeta.ac.id/index.php/betaJTM/article/view/146.