Zadoianchuk, N. V. “H-Solvability of the Optimal Control Problem for a Degenerate Elliptic Variational Inequality”. Reports of the National Academy of Sciences of Ukraine, no. 8 (August 28, 2015): 21–27. Accessed June 20, 2026. https://nasu-periodicals.org.ua/index.php/dp/article/view/15139.