Shen, Yijie V5-SHEN-11.mp4 video illustration of SHEN spheres for (n, m) = (1,1) Physical Optics 2019-03-13
    https://opticapublishing.figshare.com/articles/media/V5-SHEN-11_mp4/7323884
10.6084/m9.figshare.7323884.v1