@article{RM_1990_45_6_a3,
     author = {Nguyen Tien Zung and A. T. Fomenko},
     title = {Topological classification of integrable non-degenerate {Hamiltonians} on a~constant energy three-dimensional sphere},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {109--135},
     publisher = {mathdoc},
     volume = {45},
     number = {6},
     year = {1990},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1990_45_6_a3/}
}