@article{DAN_1967_172_1_a13,
     author = {L. P. Shilnikov},
     title = {Existence of a countable set of periodic motions in a four-dimensional space in an extended neighborhood of a saddle-focus},
     journal = {Doklady Akademii Nauk},
     pages = {54--57},
     publisher = {mathdoc},
     volume = {172},
     number = {1},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_172_1_a13/}
}