V. V. Zozulya,  A High Order Theory for Functionally Graded Shell.   journal   = {International Journal of Materials and Metallurgical Engineering}, [online]. World Academy of Science, Engineering and Technology.
    November 2011, vol. 59(11). 1039 - 1044
    [viewed 20 April 2024]. Available from: https://publications.waset.org/pdf/1240.