Nakayasu, Atsushi, and Piotr Rybka. “Integrability of the Derivative of Solutions to a Singular One-Dimensional Parabolic Problem”. Topological Methods in Nonlinear Analysis 52, no. 1 (August 4, 2018): 239–257. Accessed January 17, 2022. https://apcz.umk.pl/TMNA/article/view/TMNA.2018.031.