Columbia subject headings:
Inorganic compounds--Environmental aspects--Congresses.
Soil pollution--Congresses.
Zone of aeration--Congresses.
Harvard subject headings:
Inorganic compounds--Environmental aspects--Congresses.
Inorganic soil pollutants.
Soil pollution--Congresses
Zone of aeration--Congresses.
Princeton subject headings:
Inorganic compounds--Environmental aspects--Congresses.
Soil pollution--Congresses.
Zone of aeration--Congresses.