Columbia subject headings:
Biogeochemistry--Congresses.
Environmental health--Congresses.
Trace elements--Environmental aspects--Congresses.
Harvard subject headings:
Biogeochemistry--Congresses.
Environmental health--Congresses
Trace elements--Environmental aspects--Congresses
Princeton subject headings:
Biogeochemistry--Congresses.
Environmental health--Congresses.
Trace elements--Environmental aspects--Congresses.