Maximal and Minimal Solutions to a Class of Elliptic Quasilinear Problems
Giovanni Maria Troianiello · Proceedings of the American Mathematical Society · 1984
We prove existence of maximal and minimal solutions to bilateral problems for quasilinear elliptic operators with nondivergence principal part independent of the gradient. This result also covers the case of equations, when the obstacles can be taken as lower and upper solutions.