Columbia subject headings:
Metals--Analysis--Congresses.
Metals--Physiological effect--Congresses.
Trace elements--Analysis--Congresses.
Harvard subject headings:
Metals--Analysis--Congresses.
Metals--Physiological effect--Congresses.
Ultratrace analysis--Congresses.
Princeton subject headings:
Metals--Analysis--Congresses.
Metals--Physiological effect--Congresses.
Ultratrace analysis--Congresses.