@book{PPN593814983, title = {Principien der Fl\"achentheorie Teil 2}, series = {GDML\_Books}, publisher = {Koch}, year = {1890}, language = {de}, url = {http://dml.mathdoc.fr/item/PPN593814983} }
Hoppe, Reinhold. Principien der Flächentheorie Teil 2. GDML_Books (1890), http://gdmltest.u-ga.fr/item/PPN593814983/