@article{DAN_1976_226_6_a13,
     author = {A. I. Neishtadt},
     title = {Averaging in multifrequency {systems.~II}},
     journal = {Doklady Akademii Nauk},
     pages = {1295--1298},
     publisher = {mathdoc},
     volume = {226},
     number = {6},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1976_226_6_a13/}
}