Columbia subject headings:
Architecture--Italy--Bologna--Guidebooks.
Bologna (Italy)--Buildings, structures, etc.--Guidebooks.
Harvard subject headings:
Architecture--Italy--Bologna--Guidebooks.
Bologna (Italy)--Buildings, structures, etc.--Guidebooks.
Princeton subject headings:
Architecture--Italy--Bologna--Guidebooks.
Bologna (Italy)--Buildings, structures, etc--Guidebooks.
Guidebooks.