@article{VMUMM_1990_2_a6,
     author = {S. V. Bolotin},
     title = {Integrable {Birkhoff} billiards},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {33--36},
     publisher = {mathdoc},
     number = {2},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1990_2_a6/}
}