Chun-Yao Lee and  Hung-Chi Lin,  Analysis of Vibration Signal of DC Motor Based on Hilbert-Huang Transform.   journal   = {International Journal of Electrical and Computer Engineering}, [online]. World Academy of Science, Engineering and Technology.
    December 2010, vol. 48(12). 1722 - 1724
    [viewed 01 June 2020]. Available from: https://publications.waset.org/pdf/5949.