Chepurukhina, I. S. “A Semihomogeneous Elliptic Problem With Additional Unknown Functions in Boundary Conditions”. Reports of the National Academy of Sciences of Ukraine, no. 7 (July 28, 2015): 20–28. Accessed June 20, 2026. https://nasu-periodicals.org.ua/index.php/dp/article/view/15067.