@article{DAN_1961_141_6_a4,
     author = {A. Yu. Levin},
     title = {On the stability of solutions of second-order equations},
     journal = {Doklady Akademii Nauk},
     pages = {1298--1301},
     publisher = {mathdoc},
     volume = {141},
     number = {6},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1961_141_6_a4/}
}