L. Escauriaza et Ce. Kenig, AREA INTEGRAL ESTIMATES FOR SOLUTIONS AND NORMALIZED ADJOINT SOLUTIONS TO NONDIVERGENCE FORM ELLIPTIC-EQUATIONS, Arkiv for matematik, 31(2), 1993, pp. 275-296
We show that the L(p) norms, 0<p<infinity, of the nontangential maxima
l function and area integral of solutions and normalized adjoint solut
ions to second order nondivergence form elliptic equations, are compar
able when integrated on the boundary of a Lipschitz domain with respec
t to measures, which are respectively A(infinity) with respect to the
corresponding harmonic measure or normalized harmonic