Hema, D. P. ., K. Padmavathi, and B. N. Reddy. “CNC MACHINING OF ALLOY STEEL 4130 AND OPTIMIZATION OF PROCESS PARAMETERS”. International Journal of Technical Innovation in Modern Engineering & Science, vol. 5, no. 2, Feb. 2019, pp. 295-03, https://ijtimes.com/index.php/ijtimes/article/view/2380.