@article{SM_1997_188_2_a6,
     author = {P. I. Topalov},
     title = {Tensor invariants of natural mechanical systems on compact surfaces, and the~corresponding integrals},
     journal = {Sbornik. Mathematics},
     pages = {307--326},
     year = {1997},
     volume = {188},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1997_188_2_a6/}
}