Boukhzer Abdenbi and  El Bikri Khalid and  Benamar Rhali,  Geometrically Non-Linear Free Vibration Analysis of Functionally Graded Rectangular Plates.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    November 2013, vol. 83(11). 2306 - 2310
    [viewed 29 February 2020]. Available from: https://publications.waset.org/pdf/9996658.