@article{DE_2003_39_6_a2,
     author = {A. Yu. Kolesov and A. N. Kulikov and N. Kh. Rozov},
     title = {Invariant {Tori} of a {Class} of {Point} {Transformations:} {Preservation} of an {Invariant} {Torus} {Under} {Perturbations}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {738--753},
     publisher = {mathdoc},
     volume = {39},
     number = {6},
     year = {2003},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2003_39_6_a2/}
}