@article{DAN_1966_171_2_a4,
     author = {P. P. Zabreiko and I. B. Ledovskaya},
     title = {Higher order approximations of the averaging method of {N.} {N.~Bogoljubov{\textendash}N.} {M.~Krylov}},
     journal = {Doklady Akademii Nauk},
     pages = {262--265},
     year = {1966},
     volume = {171},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1966_171_2_a4/}
}