@article{MZ_1989__201_4_174031,
     author = {Willberd van der Kallen},
     title = {Longest {Weight} {Vectors} and {Excellent} {Filtrations.}},
     journal = {Mathematische Zeitschrift},
     pages = {19--32},
     publisher = {mathdoc},
     volume = {201},
     number = {4},
     year = {1989},
     zbl = {0642.20037},
     url = {http://geodesic.mathdoc.fr/item/MZ_1989__201_4_174031/}
}