N. Chegeni and  M. J. Tahmasebi Birgani,  Equivalent Field Calculation to Irregular Symmetric and Asymmetric Photon Fields.   journal   = {International Journal of Physical and Mathematical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    September 2013, vol. 81(9). 1430 - 1435
    [viewed 19 April 2024]. Available from: https://publications.waset.org/pdf/16724.