Columbia subject headings:
Painting, German--19th century--Criticism and interpretation.
Warthmüller, Robert, 1859-1895--Criticism and interpretation.
Harvard subject headings:
Frederick II, King of Prussia, 1712-1786--Portraits.
Warthmüller, Robert, 1859-1895--Criticism and interpretation.
Princeton subject headings:
Frederick II, King of Prussia, 1712-1786--Portraits.
Warthmüller, Robert, 1859-1895--Criticism and interpretation.