@article{VMUMM_2014_4_a2,
     author = {V. V. Fokicheva},
     title = {Description of singularities for billiard systems bounded by confocal ellipses or hyperbolas},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {18--27},
     publisher = {mathdoc},
     number = {4},
     year = {2014},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2014_4_a2/}
}