Arti Vaish and  Harish Parthasarathy,  Action Functional of the Electomagnetic Field: Effect of Gravitation.   journal   = {International Journal of Physical and Mathematical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    August 2010, vol. 44(8). 1220 - 1226
    [viewed 26 April 2024]. Available from: https://publications.waset.org/pdf/5828.