Columbia subject headings:
Iron industry and trade--Germany--Aachen--History.
Harvard subject headings:
Iron--Germany--Aachen--Metallurgy--History.
Metallurgy--Germany--Aachen--History.
Rheinisch-Westfälische Technische Hochschule Aachen. Institut für Eisenhüttenkunde--History.
Steel--Metallurgy--History.
Princeton subject headings:
Iron--Germany--Aachen--Metallurgy--History.
Metallurgy--Germany--Aachen--History.
Rheinisch-Westfälische Technische Hochschule Aachen. Institut für Eisenhüttenkunde--History.
Steel--Metallurgy--History.