Bazalii, B. V., & Tedeev, A. F. (1993). Symmetrization and initial boundary-value problems for certain classes of nonlinear second order parabolic equations.
Ukrains’kyi Matematychnyi Zhurnal,
45(7), 884–892.
https://umj.imath.kiev.ua/index.php/umj/article/view/5880