@article{AM2_1978__17_136729, author = {H. Schwerdtfeger}, title = {Invariants of a class of transformation groups {II.} {(Short} {Communication).}}, journal = {Aequationes mathematicae}, pages = {114--114}, year = {1978}, volume = {17}, zbl = {0393.39006}, url = {http://geodesic.mathdoc.fr/item/AM2_1978__17_136729/} }