CHEPURUKHINA, I. S. A semihomogeneous elliptic problem with additional unknown functions in boundary conditions . Reports of the National Academy of Sciences of Ukraine, Kyiv, Ukraine, n. 7, p. 20–28, 2015. DOI: 10.15407/dopovidi2015.07.020. Disponível em: https://nasu-periodicals.org.ua/index.php/dp/article/view/15067. Acesso em: 20 jun. 2026.