@article{VMUMM_2006_6_a1,
     author = {T. A. Lepskii},
     title = {The monodromy operator of an integrable system $(\mathbb R^4,\omega,H)$ under the condition of the incompleteness of skew-symmetric fields},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {6--10},
     publisher = {mathdoc},
     number = {6},
     year = {2006},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2006_6_a1/}
}