@book{PPN236008730, title = {Theoretische Astronomie Bd. 7}, series = {GDML\_Books}, year = {1906}, language = {lat}, url = {http://dml.mathdoc.fr/item/PPN236008730} }
(éd.). Theoretische Astronomie Bd. 7. GDML_Books (1906), http://gdmltest.u-ga.fr/item/PPN236008730/