@article{TRSPY_2007_259_a11,
     author = {M. B. Sevryuk},
     title = {Partial {Preservation} of {Frequencies} and {Floquet} {Exponents} in {KAM} {Theory}},
     journal = {Informatics and Automation},
     pages = {174--202},
     publisher = {mathdoc},
     volume = {259},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_2007_259_a11/}
}