van Wijk, Kasper Ray in a sphere with a constant v Ray in a sphere with a constant v ray tracing;constant v;epicentral distance;Geophysics 2019-04-02
    https://auckland.figshare.com/articles/figure/Ray_in_a_sphere_with_a_constant_v/7940828
10.17608/k6.auckland.7940828.v2