Columbia subject headings:
Harvard subject headings:
Coal miners--Labor unions--Spain--Puertollano--History--19th century.
Coal miners--Labor unions--Spain--Puertollano--History--20th century.
Labor movements--Spain--Puertollano--History--19th century.
Labor movements--Spain--Puertollano--History--20th century.
Princeton subject headings:
Coal miners--Labor unions--Spain--Puertollano.
Coal miners--Spain--Puertollano.
Labor movement--Spain--Puertollano.
Puertollano (Spain)--History.