@article{JCA_2003_10_2_JCA_2003_10_2_a6,
     author = {K. Zhang},
     title = {On the {Equal} {Hull} {Problem} for {Nontrivial} {Semiconvex} {Hulls}},
     journal = {Journal of convex analysis},
     pages = {409--417},
     publisher = {mathdoc},
     volume = {10},
     number = {2},
     year = {2003},
     url = {http://geodesic.mathdoc.fr/item/JCA_2003_10_2_JCA_2003_10_2_a6/}
}