XI. Kapitel. Die Flächen 2. Grades.
Lehrbuch der darstellenden Geometrie Bd. 2, GDML_Books, (1896), p. 153 / Harvested from
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@article{PPN592034941+DMDLOG_0007,
     title = {XI. Kapitel. Die Fl\"achen 2. Grades.},
     booktitle = {Lehrbuch der darstellenden Geometrie Bd. 2},
     series = {GDML\_Books},
     publisher = {Veit},
     year = {1896},
     pages = {153},
     url = {http://dml.mathdoc.fr/item/PPN592034941+DMDLOG_0007}
}

 (éd.). XI. Kapitel. Die Flächen 2. Grades., dans Lehrbuch der darstellenden Geometrie Bd. 2, GDML_Books,  (1896), p. 153. http://gdmltest.u-ga.fr/item/PPN592034941+DMDLOG_0007/