Columbia subject headings:
Harvard subject headings:
Iron industry and trade--Great Britain--History
Nail industry--Great Britain--History.
P. MacCallum & Sons Ltd.--History.
Shipbuilding industry--Great Britain--History.
Steel industry and trade--Great Britain--History
Princeton subject headings:
Iron industry and trade--Scotland--Greenock (Renfrew).
P. MacMallum & Sons--History.
Stell industry and trade--Scotland--Greenock (Renfrew)