@article{BAG_1992__33_138503,
     author = {U. STERZ and K. DRECHSLER},
     title = {Contact {Conditions} on {Conic} {Varieties} and {Halphen's} 2nd {Formula}},
     journal = {Beitr\"age zur Algebra und Geometrie},
     pages = {55--70},
     publisher = {mathdoc},
     volume = {33},
     year = {1992},
     zbl = {0769.14020},
     url = {http://geodesic.mathdoc.fr/item/BAG_1992__33_138503/}
}