I. B. Romanenko and I. V. Skrypnik, “A priori estimates of solutions of linear parabolic problems with coefficients from Sobolev spaces”, Ukr. Mat. Zhurn., vol. 51, no. 11, pp. 1534–1548, Nov. 1999, Accessed: Dec. 05, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/4755