@article{CMUC_1976__17_1_a15,
     author = {Dane\v{s}, Josef and Durdil, Ji\v{r}{\'\i}},
     title = {A note on geometric characterization of {Fr\'echet} differentiability},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {195--204},
     publisher = {mathdoc},
     volume = {17},
     number = {1},
     year = {1976},
     mrnumber = {0415663},
     zbl = {0321.58009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1976__17_1_a15/}
}