Columbia subject headings:
Harvard subject headings:
Frederick William IV, King of Prussia, 1795-1861--Correspondence.
Humboldt, Alexander von, 1769-1859--Correspondence.
Prussia (Germany)--History--Frederick William IV, 1840-1861--Sources.
Prussia (Germany)--Kings and rulers--Correspondence.
Science--Germany--History--Sources.
Scientists--Germany--Correspondence.
Scientists--Germany--Prussia--Correspondence.
Princeton subject headings:
Frederick William IV, King of Prussia, 1795-1861--Correspondence.
Humboldt, Alexander von, 1769-1859--Correspondence.
Prussia (Germany)--History--Frederick William IV, 1840-1861--Sources.
Prussia (Germany)--Kings and rulers--Correspondence.
Science--Germany--History--Sources.
Scientists--Germany--Prussia--Correspondence.