%0 Journal Article %A P. I. Topalov %T Tensor invariants of natural mechanical systems on compact surfaces, and theĀ corresponding integrals %J Sbornik. Mathematics %D 1997 %P 307-326 %V 188 %N 2 %U http://geodesic.mathdoc.fr/item/SM_1997_188_2_a6/ %G en %F SM_1997_188_2_a6