@article{PMIHES_1990__72__5_0,
     author = {S. Hurder and Anatoly Katok},
     title = {Differentiability, rigidity and {Godbillon-Vey} classes for {Anosov} flows},
     journal = {Publications Math\'ematiques de l'IH\'ES},
     pages = {5--61},
     year = {1990},
     publisher = {Institut des Hautes \'Etudes Scientifiques},
     volume = {72},
     doi = {10.1007/BF02699130},
     mrnumber = {92b:58179},
     zbl = {0725.58034},
     language = {en},
     url = {https://pmihes.centre-mersenne.org/articles/10.1007/BF02699130/}
}