@article{JCA_1998_5_2_a1,
     author = {J. M. Borwein and Q. J. Zhu},
     title = {Limiting {Convex} {Examples} for {Nonconvex} {Subdifferential} {Calculus}},
     journal = {Journal of convex analysis},
     pages = {221--236},
     year = {1998},
     volume = {5},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/JCA_1998_5_2_a1/}
}