@article{RM_1972_27_3_a13,
     author = {V. F. Lazutkin},
     title = {Existence of a~continuum of closed invariant curves for a~convex billiard},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {27},
     number = {3},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1972_27_3_a13/}
}