Unimprovable estimates for solutions of a mixed problem for linear elliptic equations of the second order in a neighborhood of an angular point

Under the minimal conditions for the smoothness of the coefficients of an equation, unimprovable estimates are obtained for solutions of a mixed problem for linear nondivergent elliptic equations of the second order in a neighborhood of an angular point of the boundary of a domain. Lviv University, Lviv. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 49, No. 11, pp. 1529–1542, November, 1997.