Columbia subject headings:
Harvard subject headings:
Castile (Spain)--Court and courtiers--History--Congresses.
Civilization, Medieval--Congresses
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Frederick II, Holy Roman Emperor, 1194-1250--Knowledge--Natural history--Congresses.
History
Knowledge, Sociology of--Congresses.
Learning and scholarship--Italy--Sicily--History--Congresses.
Middle Ages--Congresses
Sicily (Italy)--Court and courtiers--History--Congresses.
Princeton subject headings:
History--Europe.
Middle Ages--Congresses.