PlaksaS. A. “Dirichlet Problem for Axisymmetric Potential Fields in a Disk of the Meridian Plane. I”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 52, no. 4, Apr. 2000, pp. 492-11, https://umj.imath.kiev.ua/index.php/umj/article/view/4439.