@article{DE_1979_15_11_a23,
     author = {V. L. Khatskevich},
     title = {Application of the {Galerkin} method for determining periodic solutions of differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2100--2103},
     year = {1979},
     volume = {15},
     number = {11},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1979_15_11_a23/}
}