Shabgard, M. , Sadizadeh, B. , Kakoulvand, H. (2009), 'The Effect of Ultrasonic Vibration of Workpiece in Electrical Discharge Machining of AISIH13 Tool Steel', World Academy of Science, Engineering and Technology, Open Science Index 28, International Journal of Mechanical and Mechatronics Engineering, 3(4), 404 - 408.