Riferimenti: [https://de.wikipedia.org/wiki/Heintze_%26_Blanckertz], [https://en.wikipedia.org/wiki/Heintze_%26_Blanckertz], [https://brandenburg.museum-digital.de/object/3601?navlang=de] | Riferimenti: [https://de.wikipedia.org/wiki/Heintze_%26_Blanckertz], [https://en.wikipedia.org/wiki/Heintze_%26_Blanckertz], [https://brandenburg.museum-digital.de/object/3601?navlang=de] |