@article{NUMA_1965__7_131659,
     author = {J. FOCKE},
     title = {\"Uber die {Multiplikativit\"at} von {Matrizennormen.}},
     journal = {Numerische Mathematik},
     pages = {251--254},
     publisher = {mathdoc},
     volume = {7},
     year = {1965},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1965__7_131659/}
}