MURATBEKOV, M.B.; IGISINOV, S.J.; SHYRAKBAEV, A.B. On separability of non-classical type differential operator in an unbounded domain. Bulletin of the Karaganda University. Mathematics Series, [S. l.], v. 82, n. 2, p. 95–106, 2016. Disponível em: https://mts.buketov.edu.kz/mathematics-vestnik/article/view/116. Acesso em: 1 apr. 2026.