Harahap, Ahmad Indra, Tulus ., and Zakarias Situmorang. “Positive and Negative Impacts of Using Android-Based Smartphone Operations in Early Childhood”. The International Journal of Science & Technoledge 6, no. 7 (July 31, 2018). Accessed June 29, 2024. http://internationaljournalcorner.com/index.php/theijst/article/view/131414.