Columbia subject headings:
Frederick William IV, King of Prussia, 1795-1861.
Prussia (Duchy)--History--Frederick William IV, 1840-1861.
Harvard subject headings:
Frederick William IV, King of Prussia, 1795-1861--Congresses.
Prussia (Germany)--History--Frederick William IV, 1840-1861--Congresses.
Prussia (Germany)--Kings and rulers--Biography--Congresses.
Princeton subject headings:
Frederick William IV, King of Prussia, 1795-1861--Congresses.
Prussia (Germany)--History--Frederick William IV, 1840-1861--Congresses.
Prussia (Germany)--Kings and rulers--Biography--Congresses.