@article{SM_1993_75_2_a10,
     author = {Nguyen Tien Zung},
     title = {The complexity of integrable {Hamiltonian} systems on a~prescribed three-dimensional constant-energy submanifold},
     journal = {Sbornik. Mathematics},
     pages = {507--533},
     publisher = {mathdoc},
     volume = {75},
     number = {2},
     year = {1993},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1993_75_2_a10/}
}