@article{FAA_1973_7_2_a3,
     author = {M. M. Dvorin and V. F. Lazutkin},
     title = {The existence of an infinite number of elliptic and hyperbolic periodic trajectories for a convex billiard},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {20--27},
     publisher = {mathdoc},
     volume = {7},
     number = {2},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1973_7_2_a3/}
}