Panggabean, Jonas Franky. “Design and Manufacture of Number of People Counting Devices Using the AT89S52 Microcontroller”. Jurnal ICT : Information and Communication Technologies 13, no. 1 (April 30, 2022): 47–50. Accessed April 30, 2026. https://www.ejournal.marqchainstitute.or.id/index.php/JICT/article/view/18.