N. G. Al Jihad, M. Fatih Mufadhdhal, and R. . Aprianto, “Design and Development of a Countdown Timer System in the Passenger Pickup and Drop-off Area Based on Ultrasonic Sensor”, Jurnal Perintis, vol. 2, no. 2(Maret-April), pp. 83–91, Apr. 2026, Accessed: Apr. 29, 2026. [Online]. Available: https://ejournal.pktj.ac.id/index.php/perintis/article/view/117