Columbia subject headings:
Lead--Toxicology--Congresses.
Metals--Toxicology--Congresses.
Organohalogen compounds--Toxicology--Congresses.
Porphyria--Environmental aspects--Congresses.
Porphyrins--Metabolism--Congresses.
Harvard subject headings:
Lead--Toxicology--Congresses.
Metals--Toxicology--Congresses.
Organohalogen compounds--Toxicology--Congresses.
Porphyria--Environmental aspects--Congresses.
Porphyrins--Metabolism--Congresses.
Princeton subject headings:
Lead--Toxicology--Congresses.
Metals--Toxicology--Congresses.
Organohalogen compounds--Toxicology--Congresses.
Porphyria--Environmental aspects--Congresses.
Porphyrins--Metabolism--Congresses.