@article{IM2_1992_39_1_a2,
     author = {A. T. Fomenko},
     title = {A~bordism theory for integrable nondegenerate {Hamiltonian} systems with two degrees of freedom. {A~new} topological invariant of higher-dimensional integrable systems},
     journal = {Izvestiya. Mathematics },
     pages = {731--759},
     publisher = {mathdoc},
     volume = {39},
     number = {1},
     year = {1992},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1992_39_1_a2/}
}