U. Mutman and  S. B. Coskun,  Free Vibration Analysis of Non-Uniform Euler Beams on Elastic Foundation via Homotopy Perturbation Method.   journal   = {International Journal of Mechanical and Mechatronics Engineering}, [online]. World Academy of Science, Engineering and Technology.
    July 2013, vol. 79(7). 1353 - 1358
    [viewed 26 April 2024]. Available from: https://publications.waset.org/pdf/16353.