Columbia subject headings:
Castles--Italy--Siena (Province)--Guidebooks.
Siena (Italy : Province)--Guidebooks.
Harvard subject headings:
Castles--Italy--Siena (Province)--Guidebooks.
Siena (Italy : Province)--Guidebooks.
Princeton subject headings:
Castles--Italy--Siena (Province)--Guidebooks.
Siena (Italy : Province)--Guidebooks.