@article{DAN_1961_136_3_a8,
     author = {Ya. G. Sinai},
     title = {Geodesic flows on compact surfaces of negative curvature},
     journal = {Doklady Akademii Nauk},
     pages = {549--552},
     publisher = {mathdoc},
     volume = {136},
     number = {3},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1961_136_3_a8/}
}