Volchkov, V. V., and I. M. Savost’yanova. “Analog of the John Theorem for Weighted Spherical Means on a Sphere”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 65, no. 5, May 2013, pp. 611–619, https://umj.imath.kiev.ua/index.php/umj/article/view/2445.