Mohamed M. Mousa and  Aidarkhan Kaltayev,  Solving Inhomogeneous Wave Equation Cauchy Problems using Homotopy Perturbation Method.   journal   = {International Journal of Physical and Mathematical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    July 2009, vol. 31(7). 490 - 493
    [viewed 26 April 2024]. Available from: https://publications.waset.org/pdf/7335.