Columbia subject headings:
Cave architecture--Italy--Sicily--Congresses.
Cave churches--Italy--Sicily--Congresses.
Excavations (Archaeology)--Italy--Sicily--Congresses.
Sicily (Italy)--Antiquities--Congresses.
Harvard subject headings:
Cave architecture--Italy--Sicily--Congresses.
Cave churches--Italy--Sicily--Congresses.
Excavations (Archaeology)--Italy--Sicily--Congresses.
Sicily (Italy)--Antiquities--Congresses.
Princeton subject headings:
Excavations (Archaeology)--Italy--Sicily--Congresses.
Sicily (Italy)--Antiquities--Congresses.
Sicily (Italy)--Civilization--Congresses.