Columbia subject headings:
Groundwater--Pollution--Congresses.
Groundwater--Quality--Congresses.
Water chemistry--Congresses.
Water quality management--Congresses.
Water quality--Congresses.
Water--Pollution--Congresses.
Harvard subject headings:
Princeton subject headings:
Groundwater--Pollution--Congresses.
Groundwater--Quality--Congresses.
Water chemistry--Congresses.
Water quality management--Congresses.
Water quality--Congresses.
Water--Pollution--Congresses.