@article{10_1090_S1079_6762_05_00151_4,
     author = {Ledrappier, Fran\c{c}ois and Sarig, Omri},
     title = {Invariant measures for the horocycle flow on periodic hyperbolic surfaces},
     journal = {Electronic research announcements of the American Mathematical Society},
     pages = {89--94},
     year = {2005},
     volume = {11},
     doi = {10.1090/S1079-6762-05-00151-4},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S1079-6762-05-00151-4/}
}