Columbia subject headings:
Harvard subject headings:
Iron and steel workers--Legal status, laws, etc.--Spain--Guipúzcoa--History.
Iron industry and trade--Law and legislation--Spain--Guipúzcoa--History.
Iron industry and trade--Spain--Guipúzcoa--History--Sources.
Iron industry and trade--Spain--Guipúzcoa--History.
Princeton subject headings:
Iron foundries--Spain--Guipúzcoa--History.
Iron trade and industry--Law and legislation--Spain--Guipuzcoa.
Iron-works--Spain--Guipúzcoa--History.