MikhailetsV. A., and MurachA. A. “Improved Scales of Spaces and Elliptic Boundary-Value Problems. II”. Ukrains’kyi Matematychnyi Zhurnal 58, no. 3 (March 25, 2006): 352–370. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3459.