@article{NUMA_1972__20_132188,
     author = {Richard S. Varga and Bernard W. Levinger},
     title = {On {Minimal} {Gerschgorin} {Sets} for {Families} of {Norms.}},
     journal = {Numerische Mathematik},
     pages = {252--256},
     publisher = {mathdoc},
     volume = {20},
     year = {1972},
     zbl = {0302.65029},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1972__20_132188/}
}