Columbia subject headings:
Communication--Political aspects--Germany--Congresses.
Nobility--Germany--Congresses.
Harvard subject headings:
Communication--Political aspects--Germany--Congresses.
Knights and knighthood--Germany--History--Congresses.
Knights and knighthood--History--Congresses.
Nobility--Germany--Congresses.
Nobility--Germany--History--Congresses.
Nobility--History--Congresses.
Telecommunication systems--Germany--History--To 1500--Congresses.
Telecommunication systems--History--To 1500--Congresses.
Princeton subject headings:
Knights and knighthood--Germany--History--Congresses.
Knights and knighthood--History--Congresses.
Nobility--Germany--History--Congresses.
Nobility--History--Congresses.
Telecommunication systems--Germany--History--To 1500--Congresses.
Telecommunication systems--History--To 1500--Congresses.