@article{JCA_1996_3_2_a8,
     author = {E. El Haddad and R. Deville},
     title = {The {Viscosity} {Subdifferential} of the {Sum} of {Two} {Functions} in {Banach} {Spaces.} {I:} {First} {Order} {Case}},
     journal = {Journal of convex analysis},
     pages = {295--308},
     publisher = {mathdoc},
     volume = {3},
     number = {2},
     year = {1996},
     url = {http://geodesic.mathdoc.fr/item/JCA_1996_3_2_a8/}
}