Columbia subject headings:
Ascoli Piceno (Italy)--History--Congresses.
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Harvard subject headings:
Ascoli Piceno (Italy)--History--Congresses.
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Princeton subject headings:
Ascoli Piceno (Italy)--History--Congresses.
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.