Dinh, Van Thanh, et al. “Multi-Objective Optimization of Material Removal Rate and Surface Roughness in Ultrasonic Vibration-Assisted EDM Using NSGA-II, GPR, and AHP”. Engineering, Technology & Applied Science Research, vol. 15, no. 4, Aug. 2025, pp. 24977-84, doi:10.48084/etasr.11380.