@article{SM_1995_186_3_a2,
     author = {S. I. Dudov},
     title = {Directional differentiability of the distance function},
     journal = {Sbornik. Mathematics},
     pages = {337--358},
     publisher = {mathdoc},
     volume = {186},
     number = {3},
     year = {1995},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1995_186_3_a2/}
}