PORTNYAHIN, D. V. Boundedness of weak solutions of a nondiagonal parabolic system of two equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 61, n. 3, p. 400–407, 2009. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3028. Acesso em: 6 dec. 2025.