@article{MZ_1988__198_3_173914,
     author = {Stephen Donkin},
     title = {Invariants of {Unipotent} {Radicals.}},
     journal = {Mathematische Zeitschrift},
     pages = {117--126},
     year = {1988},
     volume = {198},
     number = {3},
     zbl = {0627.14013},
     url = {http://geodesic.mathdoc.fr/item/MZ_1988__198_3_173914/}
}