Kaźmierczak, B. “Existence of Travelling Wave Solutions for Reaction-Diffusion-Convection Systems via the Conley Index Theory”. Topological Methods in Nonlinear Analysis, vol. 17, no. 2, June 2001, pp. 359-03, https://apcz.umk.pl/TMNA/article/view/TMNA.2001.020.