@article{MZ_1988__197_1_183728,
     author = {Rainer Wittmann},
     title = {Ein starkes },
     journal = {Mathematische Zeitschrift},
     pages = {223--230},
     year = {1988},
     volume = {197},
     number = {1},
     url = {http://geodesic.mathdoc.fr/item/MZ_1988__197_1_183728/}
}