@article{DAN_1974_214_4_a1,
     author = {V. S. Afraimovich and L. P. Shilnikov},
     title = {On small periodic perturbations of autonomous systems},
     journal = {Doklady Akademii Nauk},
     pages = {739--742},
     publisher = {mathdoc},
     volume = {214},
     number = {4},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_214_4_a1/}
}