@article{AM2_1978__17_136746,
     author = {H. Schwerdtfeger},
     title = {Invariants of a class of transformation groups {II.}},
     journal = {Aequationes mathematicae},
     pages = {292--294},
     year = {1978},
     volume = {17},
     zbl = {0393.39006},
     url = {http://geodesic.mathdoc.fr/item/AM2_1978__17_136746/}
}