@article{NUMA_1968__12_131859,
     author = {J. STOER},
     title = {Lower {Bounds} of {Matrices.}},
     journal = {Numerische Mathematik},
     pages = {146--158},
     year = {1968},
     volume = {12},
     zbl = {0174.31902},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1968__12_131859/}
}