@article{IVM_1973_12_a3,
     author = {I. M. Vul'pe},
     title = {Generalization of the averaging method of {N.\,N.~Bogolyubov} to certain classes of differential equations without mean values},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {28--32},
     publisher = {mathdoc},
     number = {12},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1973_12_a3/}
}