Pertiwi, N., U. S. Saud, and Y. N. V. Saffitri. “Utilization of the WhatsApp-Based Internet for Elementary School Students During the Covid-19 Pandemic”. International Conference on Elementary Education, Vol. 3, no. 1, Apr. 2021, pp. 126-32, https://proceedings.upi.edu/index.php/icee/article/view/1453.