@article{104789, author = {Robert Karpe}, title = {Verallgemeinerung der goniometrischen Funktionen}, journal = {Archivum Mathematicum}, volume = {009}, year = {1973}, pages = {26-48}, zbl = {0282.50004}, mrnumber = {0362007}, language = {de}, url = {http://dml.mathdoc.fr/item/104789} }
Karpe, Robert. Verallgemeinerung der goniometrischen Funktionen. Archivum Mathematicum, Tome 009 (1973) pp. 26-48. http://gdmltest.u-ga.fr/item/104789/
O rovnicích, Praha, r. 1947. (1947)