Columbia subject headings:
Catholic labor unions--Germany--History.
Church and social problems--Germany--History.
Labor unions--Religious aspects--Christianity--Germany--History.
Miners--Labor unions--Germany--History.
Harvard subject headings:
Catholic labor unions--Germany--History.
Church and social problems--Germany--History.
Labor unions--Germany--History
Labor unions--Religious aspects--Christianity
Labor unions--Religious aspects--Christianity--Germany--History.
Miners--Labor unions--Germany--History.
Princeton subject headings:
Catholic labor unions--Germany--History.
Church and social problems--Germany--History.
Labor unions--Religious aspects--Christianity--Germany--History.
Miners--Labor unions--Germany--History.