Skrypnik, I. I. “Regularity of a Boundary Point for Singular Parabolic Equations With Measurable Coefficients”. Ukrains’kyi Matematychnyi Zhurnal 56, no. 4 (April 25, 2004): 506–516. Accessed April 30, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3772.