W. S. M. Sanjaya, D. Anggraeni, R. Denya, H. Pandriantama, I. Iklimah, and I. P. Dewi, “A Low Cost Of Simple Pendulum Experiment Apparatus Based On Ultrasonic Sensor And Arduino Microcontroller”, JAK, vol. 1, no. 2, pp. 61–66, Sep. 2018.