V. P. Burskii, “Boundary-value problems for an elliptic equation with complex coefficients and a certain moment problem”, Ukr. Mat. Zhurn., vol. 45, no. 11, pp. 1476–1483, Nov. 1993, Accessed: Apr. 23, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5954