ВarkovskyV. V., & RoitbergY. A. (1966). On the minimum and maximum operator corresponding to the general elliptical problem with inhomogeneous boundary value conditions . Ukrains’kyi Matematychnyi Zhurnal, 18(2), 91-97. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/8719