Columbia subject headings:
Export marketing--United States--Planning.
Water--Purification--United States.
Harvard subject headings:
Export marketing--United States--Planning.
Water--Purification--United States.
Princeton subject headings:
Directories.
Export marketing--United States.
Sanitary districts--Developing countries--Directories.
Water pollution control equipment industry--United States.
Water purification equipment industry--United States.
Water quality management--Developing countries--Equipment and supplies--Marketing.
Water--Purification--Developing countries--Equipment and supplies--Marketing.