@article{LJM_1999_4_a4,
     author = {H. Sato},
     title = {Schwarzian derivatives of contact diffeomorphisms},
     journal = {Lobachevskii journal of mathematics},
     pages = {89--98},
     year = {1999},
     volume = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/LJM_1999_4_a4/}
}