@article{VMUMM_2020_4_a1,
     author = {I. S. Kharcheva},
     title = {Isoenergy manifolds of integrable billiard books},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {12--22},
     year = {2020},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2020_4_a1/}
}