@article{NUMA_1987__55_4_133377,
     author = {Marcin Studniarski},
     title = {An {Algorithm} for {Calculating} {One} {Subgradient} of a {Convex} {Function} of {Two} {Variables.}},
     journal = {Numerische Mathematik},
     pages = {685--694},
     publisher = {mathdoc},
     volume = {55},
     number = {4},
     year = {1987},
     zbl = {0671.65044},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1987__55_4_133377/}
}