@article{DAN_1979_249_1_a9,
     author = {A. A. Martynyuk},
     title = {A generalization of the second theorem of {N.\,N.~Bogolyubov's} averaging principle},
     journal = {Doklady Akademii Nauk},
     pages = {46--48},
     publisher = {mathdoc},
     volume = {249},
     number = {1},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1979_249_1_a9/}
}