Anop, A. V., and T. Kasirenko. “Elliptic Boundary-Value Problems in Hörmander Spaces”. Methods of Functional Analysis and Topology 22, no. 4 (December 25, 2016): 295–310. Accessed December 17, 2025. https://zen.imath.kiev.ua/index.php/mfat/article/view/643.