@book{PPN592152413, title = {Aufgaben Band 1}, series = {GDML\_Books}, publisher = {Koch}, year = {1865}, language = {de}, url = {http://dml.mathdoc.fr/item/PPN592152413} }
Martus, Hermann Carl Eberhard. Aufgaben Band 1. GDML_Books (1865), http://gdmltest.u-ga.fr/item/PPN592152413/