Dmytryshyn M, Lopushansky O. Spectral approximations of strongly degenerate elliptic differential operators. Carpathian Math. Publ. [Internet]. 2019 Jun. 30 [cited 2024 Nov. 24];11(1):48-53. Available from: https://journals.pnu.edu.ua/index.php/cmp/article/view/1507