The Nonlinear Boundary Value Problems of Three Elements for the First Order Quasilinear Elliptic Systems. Journal of Partial Differential Equations, [S. l.], v. 5, n. 1, p. 90–96, 1992. Disponível em: https://gsp.tricubic.dev/jpde/article/view/3706. Acesso em: 15 mar. 2026.