Columbia subject headings:
Metals--Environmental aspects--Congresses.
Trace elements--Analysis--Congresses.
Harvard subject headings:
Metals--Environmental aspects--Congresses.
Metals--Speciation--Congresses.
Trace elements--Analysis--Congresses.
Trace elements--Speciation--Congresses.
Princeton subject headings:
Metals--Environmental aspects--Congresses.
Trace elements--Analysis--Congresses.