@book{PPN63510394X, title = {Briefwechsel zwischen C. F. Gauss und H. C. Schumacher 6}, series = {GDML\_Books}, publisher = {Esch}, address = {Altona}, year = {1865}, language = {de}, url = {http://dml.mathdoc.fr/item/PPN63510394X} }
Gauss, Carl Friedrich; Schumacher, Heinrich Christian. Briefwechsel zwischen C. F. Gauss und H. C. Schumacher 6. GDML_Books (1865), http://gdmltest.u-ga.fr/item/PPN63510394X/