@article{MZ_1982__180_173184,
     author = {Nobuhiro Innami},
     title = {Differentiability of {Busemann} {Functions} and {Total} {Excess.}},
     journal = {Mathematische Zeitschrift},
     pages = {235--248},
     publisher = {mathdoc},
     volume = {180},
     year = {1982},
     zbl = {0471.53045},
     url = {http://geodesic.mathdoc.fr/item/MZ_1982__180_173184/}
}