@article{NUMA_1991__59_8_133572,
     author = {Ulrich Mertins},
     title = {Zur {Konvergenz} des {Rayleigh-Ritz-Verfahrens} bei {Eigenwertaufgaben.}},
     journal = {Numerische Mathematik},
     pages = {667--682},
     publisher = {mathdoc},
     volume = {59},
     number = {8},
     year = {1991},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1991__59_8_133572/}
}