@article{NUMA_1984__44_132931,
     author = {R.D. Lazarov and V. Makarov and W. Weinelt},
     title = {On the {Convergence} of {Difference} {Schemes} for the {Approximation} of {Solutions} {u...W...} (m>0.5) of {Elliptic} {Equations} with {Mixed} {Derivatives.}},
     journal = {Numerische Mathematik},
     pages = {223--232},
     publisher = {mathdoc},
     volume = {44},
     year = {1984},
     zbl = {0525.65069},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1984__44_132931/}
}