Columbia subject headings:
Landscape architecture--Congresses.
Trees in cities--Congresses.
Trees--Congresses.
Urban beautification--Congresses.
Harvard subject headings:
Landscape architecture--Congresses
Trees in cities--Congresses.
Trees--Congresses.
Urban beautification--Congresses.
Princeton subject headings:
Landscape architecture--Congresses.
Trees in cities--Congresses.
Trees--Congresses.
Urban beautification--Congresses.