Moklyachuk, M. P. 1995. “Robust Interpolation of Random Fields Homogeneous in Time and Isotropic on a Sphere, Which Are Observed With Noise”. Ukrains’kyi Matematychnyi Zhurnal 47 (7): 962–970. https://umj.imath.kiev.ua/index.php/umj/article/view/5491.