Aldashev, S. A., and E. T. Kitaibekov. 2017. “Well-Posedness of the Dirichlet Problem in a Cylindrical Domain for Three-Dimensional Elliptic Equations With Degeneration of Type and Order”. Ukrains’kyi Matematychnyi Zhurnal 69 (9), 1270-74. https://umj.imath.kiev.ua/index.php/umj/article/view/1778.