@article{AM_1999_149_1_a1,
     author = {N\'andor Sim\'anyi and Domokos Sz\'asz},
     title = {Hard ball systems are completely hyperbolic},
     journal = {Annals of mathematics},
     publisher = {mathdoc},
     volume = {149},
     number = {1},
     year = {1999},
     url = {http://geodesic.mathdoc.fr/item/AM_1999_149_1_a1/}
}