@article{MAN_1983__264_163786,
     author = {Charles M. Stanton},
     title = {A {Characterization} of the {Ball} by its {Intrinsic} {Metrics.}},
     journal = {Mathematische Annalen},
     pages = {271--276},
     publisher = {mathdoc},
     volume = {264},
     year = {1983},
     zbl = {0501.32002},
     url = {http://geodesic.mathdoc.fr/item/MAN_1983__264_163786/}
}