@article{FAA_1993_27_3_a4,
     author = {Nguyen Tien Zung and L. S. Polyakova and E. N. Selivanova},
     title = {Topological {Classification} of {Integrable} {Geodesic} {Flows} on {Orientable} {Two-Dimensional} {Riemannian} {Manifolds} with {Additional} {Integral} {Depending} on {Momenta} {Linearly} or {Quadratically}},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {42--56},
     publisher = {mathdoc},
     volume = {27},
     number = {3},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1993_27_3_a4/}
}