@article{ISU_2018_18_1_a2,
     author = {A. N. Kirillov and R. V. Alkin},
     title = {Stability of periodic billiard trajectories in triangle},
     journal = {Izvestiya of Saratov University. Mathematics. Mechanics. Informatics},
     pages = {25--39},
     publisher = {mathdoc},
     volume = {18},
     number = {1},
     year = {2018},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ISU_2018_18_1_a2/}
}