@article{MABA_2005_19_3-4_a6,
     author = {O. Axelsson and L. Laayouni and S. Margenov},
     title = {Robust {Multilevel} {Preconditioners} for {Second} {Order} {Elliptic} {Equations} and {Systems} of {Equations}},
     journal = {Mathematica balkanica},
     pages = {321},
     publisher = {mathdoc},
     volume = {19},
     number = {3-4},
     year = {2005},
     url = {http://geodesic.mathdoc.fr/item/MABA_2005_19_3-4_a6/}
}