@article{DAN_1963_148_2_a1,
     author = {L. N. Belyustina},
     title = {Small periodic perturbations in a structurally stable autonomous system},
     journal = {Doklady Akademii Nauk},
     pages = {251--254},
     publisher = {mathdoc},
     volume = {148},
     number = {2},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_148_2_a1/}
}