Horodets’kyi, V.V., O.V. Martynyuk, and R.S. Kolisnyk. “On a Nonlocal Problem for the First-Order Differential-Operator Equations”. Carpathian Mathematical Publications 14, no. 2 (December 30, 2022): 513–528. Accessed May 24, 2024. https://journals.pnu.edu.ua/index.php/cmp/article/view/4790.