Anop, A.V. Anop. “Lawruk Elliptic Boundaryvalue Problems for Homogeneous Differential Equations”. Reports of the National Academy of Sciences of Ukraine, no. 2 (April 15, 2024): 3–11. Accessed May 30, 2025. https://nasu-periodicals.org.ua/index.php/dp/article/view/2019-2-1.