@article{FAA_1991_25_1_a4,
     author = {N. I. Chernov},
     title = {Topological entropy and periodic points of two-dimensional hyperbolic billiards},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {50--57},
     publisher = {mathdoc},
     volume = {25},
     number = {1},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1991_25_1_a4/}
}