Columbia subject headings:
Cast-iron--Analysis.
Cast-iron--Scandinavia--History.
Iron--Analysis.
Iron--Scandinavia--History.
Steel--Analysis.
Steel--History.
Harvard subject headings:
Cast-iron--Analysis.
Cast-iron--Scandinavia--History.
Iron--Analysis
Iron--Scandinavia--History.
Steel--Analysis
Steel--History.
Princeton subject headings: