Kasirenko, T. M., and A. A. Murach. “Elliptic Problems With Boundary Conditions of Higher Orders in Hörmander Spaces”. Ukrains’kyi Matematychnyi Zhurnal 69, no. 11 (November 25, 2017): 1486-1504. Accessed April 26, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1797.