Columbia subject headings:
Harvard subject headings:
Arid regions agriculture--History--Congresses.
Arid regions ecology--Congresses.
Arid regions--Congresses
Desert people--Antiquities--Congresses.
Human settlements--History--Congresses.
Oases--History--Congresses.
Water-supply engineering--History--Congresses.
Princeton subject headings:
Arid regions agriculture--History--Congresses.
Arid regions ecology--Congresses.
Arid regions--Congresses.
Desert people--Antiquities--Congresses.
Human settlements--History--Congresses.
Oases--History--Congresses.
Water-supply engineering--History--Congresses.