@article{IM_1987__89_143471,
     author = {M. Gromov and W. Thurston},
     title = {Pinching constants for hyperbolic manifolds.},
     journal = {Inventiones mathematicae},
     pages = {1--12},
     publisher = {mathdoc},
     volume = {89},
     year = {1987},
     zbl = {0646.53037},
     url = {http://geodesic.mathdoc.fr/item/IM_1987__89_143471/}
}