N. Venkatesh, Dara Jayanth, K. S. N. N. “Weld Flaw Characterization in Ultrasonic Testing from Discrete Walsh Hadamard Transform Co-Efficient”. International Journal of Advanced Science and Technology, Vol. 28, no. 13, Nov. 2019, pp. 440 -50, http://sersc.org/journals/index.php/IJAST/article/view/1339.