@article{JCA_2011_18_4_JCA_2011_18_4_a1,
     author = {B. S. Mordukhovich and N. M. Nam},
     title = {Subgradients of {Minimal} {Time} {Functions} {Under} {Minimal} {Requirements}},
     journal = {Journal of convex analysis},
     pages = {915--947},
     publisher = {mathdoc},
     volume = {18},
     number = {4},
     year = {2011},
     url = {http://geodesic.mathdoc.fr/item/JCA_2011_18_4_JCA_2011_18_4_a1/}
}