Sapronov, D. A., and A. E. Shishkov. 2001. “Propagation of Perturbations in Quasilinear Multidimensional Parabolic Equations With Convective Term”. Ukrains’kyi Matematychnyi Zhurnal 53 (7), 953-69. https://umj.imath.kiev.ua/index.php/umj/article/view/4316.