Columbia subject headings:
Harvard subject headings:
Flour industry--Germany--Rhein-Sieg-Kreis--History.
Flour mills--Germany--Rhein-Sieg-Kreis--History.
Grain--Milling--Germany--Rhein-Sieg-Kreis--History.
Mills and mill-work--Germany--Rhein-Sieg-Kreis--History.
Water mills--Germany--Rhein-Sieg-Kreis--History.
Windmills--Germany--Rhein-Sieg-Kreis--History.
Princeton subject headings:
Flour industry--Germany--Rhein-Sieg-Kreis--History.
Flour mills--Germany--Rhein-Sieg-Kreis--History.
Grain--Milling--Germany--Rhein-Sieg-Kreis--History.
Mills and mill-work--Germany--Rhein-Sieg-Kreis--History.
Water mills--Germany--Rhein-Sieg-Kreis--History.
Windmills--Germany--Rhein-Sieg-Kreis--History.