@article{MZM_2013_93_5_a13,
     author = {S. V. Agapov and D. N. Alexandrov},
     title = {Fourth-Degree {Polynomial} {Integrals} of a {Natural} {Mechanical} {System} on a {Two-Dimensional} {Torus}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {790--793},
     publisher = {mathdoc},
     volume = {93},
     number = {5},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2013_93_5_a13/}
}