@article{ZAA_2000__19_4_48992,
     author = {Liu, Weian and Chen, Hua},
     title = {Viscosity solutions of nonlinear systems of degenerated elliptic equations of second order.},
     journal = {Zeitschrift f\"ur Analysis und ihre Anwendungen},
     pages = {927--951},
     publisher = {mathdoc},
     volume = {19},
     number = {4},
     year = {2000},
     zbl = {0976.35019},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZAA_2000__19_4_48992/}
}