@article{1104116537, author = {Hubacher, Andrea}, title = {Instability of the boundary in the billiard ball problem}, journal = {Comm. Math. Phys.}, volume = {108}, number = {1}, year = {1987}, pages = { 483-488}, language = {en}, url = {http://dml.mathdoc.fr/item/1104116537} }
Hubacher, Andrea. Instability of the boundary in the billiard ball problem. Comm. Math. Phys., Tome 108 (1987) no. 1, pp. 483-488. http://gdmltest.u-ga.fr/item/1104116537/