Jing-Gang Xie,  Gravitational Frequency Shifts for Photons and Particles.   journal   = {International Journal of Physical and Mathematical Sciences}, [online]. World Academy of Science, Engineering and Technology.
    November 2017, vol. 121(1). 1 - 5
    [viewed 19 April 2024]. Available from: https://publications.waset.org/pdf/10005968.