Plaksa, S. A. “Dirichlet Problem for an Axisymmetric Potential in a Simply Connected Domain of the Meridian Plane”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 53, no. 12, Dec. 2001, pp. 1623-41, https://umj.imath.kiev.ua/index.php/umj/article/view/4383.