WASET
    F. Abdul Majeed and  H. Karki and  Y. Abdel Magid and  M. Karkoub,  Nonlinearity and Spectrum Analysis of Drill Strings with Component Mass Unbalance.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    January 2011, vol. 49(1). 58 - 61
    [viewed 28 March 2024]. Available from: https://publications.waset.org/pdf/8888.