Columbia subject headings:
Family-owned business enterprises--Germany--Bergisches Land--History.
Small business--Germany--Bergisches Land--History.
Harvard subject headings:
Bagel family.
Family-owned business enterprises--Germany--Bergisches Land--History--19th century--Case studies.
Family-owned business enterprises--Germany--Bergisches Land--History--20th century--Case studies.
Family-owned business enterprises--Succession--Germany--Bergisches Land--Case studies.
Hard family.
Heydt family.
Small business--Germany--Bergisches Land--History--19th century--Case studies.
Small business--Germany--Bergisches Land--History--20th century--Case studies.
Princeton subject headings: