Halim, Siti Noormashetah, et al. “Let’s Calculate Kids: The Development of 3D Augmented Reality Mobile Learning Apps to Enhance Learning Engagement in Basic Calculation for Preschools”. Multidisciplinary Applied Research and Innovation, vol. 3, no. 1, Feb. 2022, pp. 60–69, https://publisher.uthm.edu.my/periodicals/index.php/mari/article/view/3520.