Columbia subject headings:
Air--Pollution--Toxicology--Congresses.
Automobiles--Motors--Exhaust gas--Analysis--Congresses.
Carcinogenesis--Congresses.
Carcinogens--Congresses.
Lungs--Cancer--Congresses.
Harvard subject headings:
Air--Pollution--Toxicology--Congresses.
Automobiles--Motors--Exhaust gas--Analysis--Congresses.
Carcinogenesis--Congresses.
Carcinogens--Congresses
Lungs--Cancer--Congresses
Princeton subject headings: