I. I. Skrypnik, “Regularity of a boundary point for singular parabolic equations with measurable coefficients”, Ukr. Mat. Zhurn., vol. 56, no. 4, pp. 506–516, Apr. 2004, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3772