@article{DAN_1969_189_5_a9,
     author = {S. D. Shmulevich},
     title = {The distribution of the eigenvalues of the operator of a selfadjoint elliptic boundary value problem in an unbounded domain},
     journal = {Doklady Akademii Nauk},
     pages = {959--962},
     publisher = {mathdoc},
     volume = {189},
     number = {5},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_189_5_a9/}
}