@article{DAN_1975_224_6_a7,
     author = {V. I. Rozhkov},
     title = {Periodic solutions of linear systems with a small parameter in the derivative},
     journal = {Doklady Akademii Nauk},
     pages = {1268--1271},
     publisher = {mathdoc},
     volume = {224},
     number = {6},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_224_6_a7/}
}