Perdana, Ferry Wahyu, Shazana Dhiya Ayuni, Arief Wisaksono, and Syamsudduha Syahrorini. “Prototype Social Distancing Reminder Using HC-SR04 Sensor At The Payment Counter Via A Smartphone”. Procedia of Engineering and Life Science 1, no. 2 (July 14, 2021). Accessed November 23, 2024. https://pels.umsida.ac.id/index.php/PELS/article/view/952.