Bazalii, B. V., and M. V. Krasnoshchok. 2004. “Classical Solvability of the First Initial Boundary-Value Problem for a Nonlinear Strongly Degenerate Parabolic Equation”. Ukrains’kyi Matematychnyi Zhurnal 56 (10): 1299-1320. https://umj.imath.kiev.ua/index.php/umj/article/view/3844.