@book{PPN517627655, title = {Das Weltsystem Theil 2}, series = {GDML\_Books}, year = {1896}, language = {ger}, url = {http://dml.mathdoc.fr/item/PPN517627655} }
(éd.). Das Weltsystem Theil 2. GDML_Books (1896), http://gdmltest.u-ga.fr/item/PPN517627655/