@article{JDM_1972__74_146613,
     author = {W. Benz and W. Leissner and H. Schaeffer},
     title = {Kreise, {Zykel,} {Ketten.} {Zur} {Geometrie} der {Algebren.}},
     journal = {Jahresbericht der Deutschen Mathematiker-Vereinigung},
     pages = {107--122},
     publisher = {mathdoc},
     volume = {74},
     year = {1972},
     zbl = {0238.50023},
     url = {http://geodesic.mathdoc.fr/item/JDM_1972__74_146613/}
}