V. A. Mikhailets and A. A. Murach, “Improved scales of spaces and elliptic boundary-value problems. II”, Ukr. Mat. Zhurn., vol. 58, no. 3, pp. 352–370, Mar. 2006, Accessed: Apr. 23, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3459