@article{DAN_1969_186_4_a4,
     author = {V. I. Derguzov},
     title = {The existence of periodic motions and motions of a special form for {Hamiltonian} systems with small parameter},
     journal = {Doklady Akademii Nauk},
     pages = {757--760},
     publisher = {mathdoc},
     volume = {186},
     number = {4},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_186_4_a4/}
}