Columbia subject headings:
Industries--Spain--Aragon--History.
Working class--Spain--Aragon--History.
Harvard subject headings:
Industrialization--Spain--Aragon--History.
Industries--Spain--Aragon--History.
Labor movement--Spain--Aragon--History.
Working class--Spain--Aragon--History.
Princeton subject headings:
Industries--Spain--Aragon--History.
Labor movement--Spain--Aragon--History.