@article{DAN_1981_257_1_a9,
     author = {A. M. Nakhushev},
     title = {On the validity of an a priori estimate},
     journal = {Doklady Akademii Nauk},
     pages = {45--47},
     year = {1981},
     volume = {257},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1981_257_1_a9/}
}