@article{NUMA_1986__49_133109,
     author = {W. Walter and C.U. Huy and P.J. McKenna},
     title = {Finite {Difference} {Approximations} to the {Dirichlet} {Problem} for {Elliptic} {Systems.}},
     journal = {Numerische Mathematik},
     pages = {227--238},
     publisher = {mathdoc},
     volume = {49},
     year = {1986},
     zbl = {0602.65068},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1986__49_133109/}
}