“Portrait of Frederick II the Great” by Anton Graff (public domain).
Source: Wikimedia Commons
“Portrait of Frederick William II” by Prussian Academy of Arts (public domain).
Source: Wikimedia Commons
“Portrait of Frederick William III” by Franz Krüger (public domain).
Source: Wikimedia Commons
Literature:
- Schrötter Friedrich, Acta Borussica…, Berlin 1904.
- Weyl Adolph, Die Paul Henckelsche Sammlung…, Berlin 1987.