@article{DAN_1964_155_4_a13,
     author = {A. V. Strauss},
     title = {On the multiplicity of the spectrum of a self-adjoint ordinary differential operator},
     journal = {Doklady Akademii Nauk},
     pages = {771--774},
     publisher = {mathdoc},
     volume = {155},
     number = {4},
     year = {1964},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1964_155_4_a13/}
}