Lavrenyuk, S. P., and M. O. Oliskevych. “Mixed Problem for a Semilinear Ultraparabolic Equation in an Unbounded Domain”. Ukrains’kyi Matematychnyi Zhurnal 59, no. 12 (December 25, 2007): 1661–1673. Accessed April 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3420.