@article{AM2_1976__14_136569,
     author = {Hans Schwerdtfeger},
     title = {Invariants of a class of transformation groups.},
     journal = {Aequationes mathematicae},
     pages = {105--110},
     publisher = {mathdoc},
     volume = {14},
     year = {1976},
     zbl = {0324.39005},
     url = {http://geodesic.mathdoc.fr/item/AM2_1976__14_136569/}
}