Columbia subject headings:
Cartels--History--Congresses.
Chemical industry--History--Congresses.
Electric industries--History--Congresses.
Trusts, Industrial--History--Congresses.
Harvard subject headings:
Cartels--History--20th century.
Cartels--History--Congresses.
Chemical industry--History--20th century.
Dye industry--History--20th century.
Electronic industries--History--20th century.
Nitrogen industries--History--1920-1939.
Trusts, Industrial--History--20th century.
Princeton subject headings:
Cartels--History--Congresses.
Chemical industry--History--Congresses.
Electric industry--History--Congresses.
Trusts, Industrial--History--Congresses.