Nishant Shrivastava and  D. K. Sehgal,  Determination of Optimal Stress Locations in 2D–9 Noded Element in Finite Element Technique.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2020, vol. 163(7). 235 - 239
    [viewed 12 August 2020]. Available from: https://publications.waset.org/pdf/10011297.