@article{DAN_1984_276_4_a4,
     author = {T. F. Pankratova},
     title = {Quasimodes and splitting of eigenvalues},
     journal = {Doklady Akademii Nauk},
     pages = {795--799},
     year = {1984},
     volume = {276},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1984_276_4_a4/}
}