@article{NUMA_1989__56_2-3_133390,
     author = {O. Axelsson and P.S. Vassilevski},
     title = {Algebraic {Multi} {Level} {Preconditioning} {Methods.} {I.}},
     journal = {Numerische Mathematik},
     pages = {157--178},
     year = {1989},
     volume = {56},
     number = {2-3},
     zbl = {0661.65110},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1989__56_2-3_133390/}
}