@article{JRAM_1972__256_151248, author = {F.W. Sch\"afke}, title = {Der }, journal = {Journal f\"ur die reine und angewandte Mathematik}, pages = {58--70}, publisher = {mathdoc}, volume = {256}, year = {1972}, zbl = {0241.28009}, url = {http://geodesic.mathdoc.fr/item/JRAM_1972__256_151248/} }