Vinod Kumar and  Jatinder Kumar,  Prediction of Tool and Nozzle Flow Behavior in Ultrasonic Machining Process.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    September 2011, vol. 57(9). 1881 - 1886
    [viewed 21 January 2020]. Available from: https://publications.waset.org/pdf/6994.