@article{IM2_1991_37_1_a9,
     author = {A. I. Zhivkov},
     title = {Geometry of invariant manifolds of a gyroscope in the field of a quadratic potential},
     journal = {Izvestiya. Mathematics },
     pages = {227--242},
     publisher = {mathdoc},
     volume = {37},
     number = {1},
     year = {1991},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1991_37_1_a9/}
}