Applications of perturbations on accretive mappings to nonlinear elliptic systems involving $(p,q)$-Laplacian. Neliniini Kolyvannya, [S. l.], v. 12, n. 2, p. 195–207, 2009. Disponível em: https://nosc.imath.kiev.ua/index.php/nosc/article/view/520. Acesso em: 12 apr. 2026.