Columbia subject headings:
Garden tours--Portugal--Guidebooks.
Garden tours--Spain--Guidebooks.
Gardens--Portugal--Guidebooks.
Gardens--Spain--Guidebooks.
Harvard subject headings:
Garden tours--Portugal--Guidebooks.
Garden tours--Spain--Guidebooks.
Gardens--Portugal--Guidebooks.
Gardens--Spain--Guidebooks.
Princeton subject headings:
Garden tours--Portugal--Guidebooks.
Garden tours--Spain--Guidebooks.
Gardens--Portugal--Guidebooks.
Gardens--Spain--Guidebooks.