Columbia subject headings:
Factory and trade waste--Arab countries.
Water quality management--Arab countries.
Water--Pollution--Arab countries.
Water--Purification--Arab countries.
Harvard subject headings:
Factory and trade waste--Arab countries.
Water quality management--Arab countries.
Water--Pollution--Arab countries.
Water--Purification--Arab countries.
Princeton subject headings:
Factory and trade waste--Purification--Arab countries.
Water quality management--Arab countries.
Water--Pollution--Arab countries.
Water--Purification--Arab countries.