@article{10_1090_S0894_0347_03_00432_6,
     author = {McMullen, Curtis},
     title = {Billiards and {Teichm\"uller} curves on {Hilbert} modular surfaces},
     journal = {Journal of the American Mathematical Society},
     pages = {857--885},
     year = {2003},
     volume = {16},
     number = {4},
     doi = {10.1090/S0894-0347-03-00432-6},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-03-00432-6/}
}