@article{DAN_1958_123_2_a9,
     author = {A. A. Shishkin},
     title = {Eigen-values and characteristic functions of some fourth order differential operators containing a small parameter in the higher derivative term},
     journal = {Doklady Akademii Nauk},
     pages = {249--251},
     publisher = {mathdoc},
     volume = {123},
     number = {2},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_123_2_a9/}
}