L. V. . Fardigola, “Correct problems in a layer with differential operators under the boundary condition”, Ukr. Mat. Zhurn., vol. 44, no. 8, pp. 1083–1090, Sep. 1992, Accessed: Apr. 07, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/8037