Zakaria Mohd Zain, M. A. Noor Rashid, S. A. Khan, and A. A. Khan, “Analysis and Modeling of Surface Roughness in Powder Mix EDM and Pure EDM Using Central Composite Design”, J. Adv. Res. Appl. Sci. Eng. Tech., vol. 30, no. 1, pp. 243–254, Mar. 2023.