@article{NUMA_1989__56_2-3_133393,
     author = {Wolfgang Hackbusch},
     title = {The {Frequency} {Decomposition} {Multi-Grid} {Method.} {Part} {I:} {Application} to {Anisotropic} {Equations.}},
     journal = {Numerische Mathematik},
     pages = {229--246},
     publisher = {mathdoc},
     volume = {56},
     number = {2-3},
     year = {1989},
     zbl = {0673.65062},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1989__56_2-3_133393/}
}