@book{PPN59009937X, title = {F\"ur obere Klassen H. 2}, series = {GDML\_Books}, publisher = {Stein}, address = {Potsdam}, year = {1883}, language = {de}, url = {http://dml.mathdoc.fr/item/PPN59009937X} }
Schubert, Hermann. Für obere Klassen H. 2. GDML_Books (1883), http://gdmltest.u-ga.fr/item/PPN59009937X/