Febrianti, A., M. Hamdi, and J. Muhammad. “Analysis of Non-Destructive Testing Ultrasonic Signal for Detection of Defective Materials Based on the Simulink Matlab Mathematica Computation Method”. Science, Technology, and Communication Journal, vol. 1, no. 2, Feb. 2021, pp. 47-60, doi:10.59190/stc.v1i2.27.