Columbia subject headings:
Castles--Great Britain--Bibliography.
Castles--Great Britain--Guidebooks.
Great Britain--Guidebooks.
Harvard subject headings:
Castles--Great Britain--Bibliography.
Castles--Great Britain--Guidebooks.
Great Britain--Guidebooks.
Princeton subject headings:
Castles--Great Britain--Bibliography.
Castles--Great Britain--Guidebooks.
Great Britain--Guidebooks.
Guidebooks.