6Zhang Q H, Zhang J H, Ren S F, et al. Study on technology of ultrasonic vibration aided electrical discharge machining in gas[J ].Journal of Materials Processing Technology, 2004, 149: 640-644.
7Leao Fabio N. Pashby Ian R. A review on the use of environmentally-friendly dielectric fluids in electrical discharge machining[J].J. of Material Processing Technology, 2004,149 : 341 - 346.