NIKITIN, A. G. Group classification of systems of nonlinear reaction-diffusion equations with triangular diffusion matrix. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 59, n. 3, p. 395–411, 2007. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3315. Acesso em: 5 dec. 2025.