@article{MOMA_1990__110_3-4_178499,
     author = {Ryszard Grzaslewicz},
     title = {Extreme {Norms} on ...},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {257--260},
     publisher = {mathdoc},
     volume = {110},
     number = {3-4},
     year = {1990},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1990__110_3-4_178499/}
}