SerovN. I., and ChernigaR. M. “Lie Symmetries, <em class="a-Plus-plus">Q</Em&gt;-Conditional Symmetries, and Exact Solutions of Nonlinear Systems of Diffusion-Convection Equations”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 55, no. 10, Oct. 2003, pp. 1340-55, https://umj.imath.kiev.ua/index.php/umj/article/view/4006.