Orlov I, Bozhonok E, Kuzmenko E. Necessary conditions for the K-extremum of a variational functional in Sobolev spaces over multi-dimensional domains . Dopov. Nac. akad. nauk Ukr. [Internet]. 2025 Feb. 17 [cited 2026 Apr. 19];(4):19-24. Available from: https://nasu-periodicals.org.ua/index.php/dp/article/view/15773