@article{AFM_2007_32_1_a19,
     author = {Henri Lind\'en},
     title = {Gromov hyperbolicity of certain conformal invariant metrics},
     journal = {Annales Fennici Mathematici},
     pages = {279--288},
     publisher = {mathdoc},
     volume = {32},
     number = {1},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AFM_2007_32_1_a19/}
}