AnopA. V., KasirenkoT. M., and MurachA. A. “Irregular Elliptic Boundary-Value Problems and Hörmander Spaces”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 70, no. 3, Mar. 2018, pp. 299-17, http://umj.imath.kiev.ua/index.php/umj/article/view/1558.