@article{NUMA_1990__57_6-7_133446,
     author = {Ziping Huang},
     title = {A {Multi-Grid} {Algorithm} for {Mixed} {Problems} with {Penalty.}},
     journal = {Numerische Mathematik},
     pages = {227--248},
     publisher = {mathdoc},
     volume = {57},
     number = {6-7},
     year = {1990},
     zbl = {0712.73106},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1990__57_6-7_133446/}
}