N. P. Protsakh, “Properties of solutions of a mixed problem for a nonlinear ultraparabolic equation”, Ukr. Mat. Zhurn., vol. 61, no. 6, pp. 795–809, Jun. 2009, Accessed: Apr. 23, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3059