@article{CMH_1930__2_138538,
     author = {Marcel Grossmann},
     title = {Darstellung des {Kreises} und der {Kegelschnitte.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {174--177},
     publisher = {mathdoc},
     volume = {2},
     year = {1930},
     zbl = {56.0534.02},
     url = {http://geodesic.mathdoc.fr/item/CMH_1930__2_138538/}
}