@article{JCA_2009_16_2_JCA_2009_16_2_a10,
     author = {C. Nour and R. J. Stern and J. Takche},
     title = {Proximal {Smoothness} and the {Exterior} {Sphere} {Condition}},
     journal = {Journal of convex analysis},
     pages = {501--514},
     publisher = {mathdoc},
     volume = {16},
     number = {2},
     year = {2009},
     url = {http://geodesic.mathdoc.fr/item/JCA_2009_16_2_JCA_2009_16_2_a10/}
}