Columbia subject headings:
Harvard subject headings:
Germany--Civilization--Italian influences--Congresses.
Germany--Foreign relations--Italy--Congresses.
Germany--History--To 1517--Congresses.
Germany--Kings and rulers--Biography--Congresses.
Holy Roman Empire--History--Congresses.
Italy--Civilization--German influences--Congresses.
Italy--Civilization--Germanic influences--Congresses.
Italy--Foreign relations--1268-1492--Congresses.
Italy--Foreign relations--476-1268--Congresses.
Italy--Foreign relations--Germany--Congresses.
Princeton subject headings:
Catholic Church--Foreign relations--Holy Roman Empire--Congresses.
Holy Roman Empire--Foreign relations--Catholic Church--Congresses.
Holy Roman Empire--Relations--Italy--Congresses.
Italy--Relations--Holy Roman Empire--Congresses.