MALYTS’KA, H. P. On the maximum principle for ultraparabolic equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 2, p. 195–201, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5347. Acesso em: 5 dec. 2025.