@article{AM2_1968__1_135969, author = {H. Schwerdtfeger}, title = {Involutory {Functions} and {Even} {Functions.} {(Short} {Communication).}}, journal = {Aequationes mathematicae}, pages = {210--210}, publisher = {mathdoc}, volume = {1}, year = {1968}, zbl = {0176.46104}, url = {http://geodesic.mathdoc.fr/item/AM2_1968__1_135969/} }