@article{DAN_1971_197_2_a6,
     author = {V. A. Pliss},
     title = {On separatrices of periodic saddle motions for periodic systems of second-order differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {275--276},
     publisher = {mathdoc},
     volume = {197},
     number = {2},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1971_197_2_a6/}
}