@article{DE_1965_1_11_a1,
     author = {V. A. Pliss},
     title = {Families of periodic solutions of systems of differential equations of second order without dissipation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1428--1448},
     publisher = {mathdoc},
     volume = {1},
     number = {11},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1965_1_11_a1/}
}