Sharvil D. Shah, Rakesh K. Bumataria, and Harshil V. Bathani. “Experimental Investigating Of Machining Parameters For EDM Using U-Shaped Electrode Of AISI P20 Tool Steel”. International Journal of Advance Research in Engineering, Science & Technology, vol. 2, no. 4, Apr. 2015, pp. 87-95, https://ijarest.org/index.php/ijarest/article/view/49.