Klevchuk, I. I. “Bifurcation of the State of Equilibrium in the System of Nonlinear Parabolic Equations With Transformed Argument”. Ukrains’kyi Matematychnyi Zhurnal, vol. 51, no. 10, Oct. 1999, pp. 1342–1351, https://umj.imath.kiev.ua/index.php/umj/article/view/4733.