@book{PPN61541169X, title = {Differential-Rechnung Theil 1}, series = {GDML\_Books}, publisher = {Helwing}, address = {Hannover}, year = {1895}, language = {de}, url = {http://dml.mathdoc.fr/item/PPN61541169X} }
Kiepert, Ludwig. Differential-Rechnung Theil 1. GDML_Books (1895), http://gdmltest.u-ga.fr/item/PPN61541169X/