Columbia subject headings:
Cadmium industry--United States--Periodicals.
Cadmium industry--United States.
Zinc industry and trade--United States--Periodicals.
Zinc industry and trade--United States.
Harvard subject headings:
Cadmium industry--United States.
Zinc industry and trade--United States.
Princeton subject headings:
Cadmium industry--United States--Periodicals.
Zinc industry and trade--United States--Periodicals.