Columbia subject headings:
Cultural geography--Germany--Rhineland--Congresses.
Cultural landscapes--Germany--Rhineland--Congresses.
Environmental management--Germany--Rhineland--Congresses.
Monuments--Conservation and restoration--Germany--Rhineland--Congresses.
Nature conservation--Germany--Rhineland--Congresses.
Harvard subject headings:
Landscape protection--Germany.
Monuments--Conservation and restoration--Germany.
Princeton subject headings: