@article{TM_2007_256_a1,
     author = {A. A. Agrachev},
     title = {The {Curvature} and {Hyperbolicity} of {Hamiltonian} {Systems}},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {31--53},
     publisher = {mathdoc},
     volume = {256},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_2007_256_a1/}
}