@article{NUMA_1990__58_5_133494,
     author = {Harry Yserentant},
     title = {Two preconditioners based on the multi-level splitting of finite element spaces.},
     journal = {Numerische Mathematik},
     pages = {163--184},
     publisher = {mathdoc},
     volume = {58},
     number = {5},
     year = {1990},
     zbl = {0708.65103},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1990__58_5_133494/}
}