@article{MZ_1993__214_1_174561,
     author = {Misha Bialy},
     title = {Convex billiards and a theorem by {E.} {Hops.}},
     journal = {Mathematische Zeitschrift},
     pages = {147--154},
     publisher = {mathdoc},
     volume = {214},
     number = {1},
     year = {1993},
     zbl = {0790.58023},
     url = {http://geodesic.mathdoc.fr/item/MZ_1993__214_1_174561/}
}