WASET
    Osama Brinji and  Wing Kong Chiu and  Graham Tew,  Investigating the Dynamic Response of the Ballast.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    February 2016, vol. 110(2). 397 - 402
    [viewed 29 March 2024]. Available from: https://publications.waset.org/pdf/10004101.