WASET
    A. Mahfurdz and  Sunardi and  H. Ahmad,  Envelope Echo Signal of Metal Sphere in the Fresh Water.   journal   = {International Journal of Electrical and Computer Engineering}, [online]. World Academy of Science, Engineering and Technology.
    May 2012, vol. 65(5). 480 - 482
    [viewed 19 April 2024]. Available from: https://publications.waset.org/pdf/7652.