An integral estimate for the gradient for a class of nonlinear elliptic equations in the plane,

An a priori estimate is established for the gradient of the solution to Dirichlet's problem for a class of nonlinear differential equations on a convex domain in the plane. The nonlinear operator is assumed to be elliptic in the sense of Campanato. By virtue of the Leray-Schauder fixed point theorem an existence result for the problem under consideration is derived