@article{VUU_2016_26_3_a9,
     author = {A. I. Safonov and O. V. Kholostova},
     title = {On the periodic motions of {a~Hamiltonian} system in the neighborhood of unstable equilibrium in the presence of a~double three-order resonance},
     journal = {Vestnik Udmurtskogo universiteta. Matematika, mehanika, kompʹ\^uternye nauki},
     pages = {418--438},
     publisher = {mathdoc},
     volume = {26},
     number = {3},
     year = {2016},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VUU_2016_26_3_a9/}
}