Columbia subject headings:
Harvard subject headings:
Germany--History--Philip of Swabia, 1198-1208--Congresses.
Germany--Kings and rulers--Assassination--Congresses.
Philipp, King of Germany, approximately 1180-1208--Congresses.
Princeton subject headings:
Germany--History--Philip of Swabia, 1198-1208--Congresses.
Philipp, King of Germany, approximately 1180-1208--Congresses.