Nanda, Is Prima, et al. “Effect of Ultrasonic Electro-Chemical Polishing Parameters on Surface Roughness and Material Removal Rate of Medical Grade Cobalt Chromium Alloys”. International Journal on Advanced Science, Engineering and Information Technology, vol. 8, no. 5, Oct. 2018, pp. 2046-51, doi:10.18517/ijaseit.8.5.4507.