MathSciDoc: An Archive for Mathematician ∫

@inproceedings{marina1984rigidity,
  title={Rigidity of time changes for horocycle flows},
  author={Marina Ratner},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203305517189380},
  booktitle={Acta Mathematica},
  volume={156},
  number={1},
  pages={1-32},
  year={1984},
}