Interior first order derivative estimates for solutions of nonlinear degenerate elliptic equations with constant coefficients
Nicolai V. Krylov · Communications in Partial Differential Equations · 1993
(1993). Interior first order derivative estimates for solutions of nonlinear degenerate elliptic equations with constant coefficients. Communications in Partial Differential Equations: Vol. 18, No. 1-2, pp. 1-40.