@article{GDZPPN002082993,
title = {Geometrical Aspects of the Circular Billiard Problem.},
journal = {Elemente der Mathematik},
volume = {47},
year = {1992},
pages = {114-117},
zbl = {0800.70052},
url = {http://dml.mathdoc.fr/item/GDZPPN002082993}
}
Hungerbühler, Norbert. Geometrical Aspects of the Circular Billiard Problem.. Elemente der Mathematik, Tome 47 (1992) pp. 114-117. http://gdmltest.u-ga.fr/item/GDZPPN002082993/