IGISINOV, S.Zh.; ZHUMALIYEVA, L.D.; SULEIMBEKOVA, A.O.; BAYANDIYEV, Ye.N. Estimates of singular numbers (s-numbers) for a class of degenerate elliptic operators. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 107, n. 3, p. 51–58, 2022. DOI: 10.31489/2022m3/51-58. Disponível em: http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/511. Acesso em: 10 jul. 2025.