@article{JRAM_1976__0283_0284_151739,
     author = {E. Heil and Volker Douglas and C. L\"ubbert},
     title = {Geradenfamilien, {Enveloppen} und {Evoluten.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {370--383},
     publisher = {mathdoc},
     volume = {0283_0284},
     year = {1976},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1976__0283_0284_151739/}
}