@article{DAN_1967_173_3_a5,
     author = {M. D. Dolberg and N. N. Yasnitskaya},
     title = {A lower boud bound for oscillation frequencies of elastic systems},
     journal = {Doklady Akademii Nauk},
     pages = {507--510},
     publisher = {mathdoc},
     volume = {173},
     number = {3},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_173_3_a5/}
}