Elena Kotevska,  Generalization Kernel for Geopotential Approximation by Harmonic Splines.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    August 2012, vol. 68(8). 992 - 998
    [viewed 11 May 2024]. Available from: https://publications.waset.org/pdf/8514.