Columbia subject headings:
Neckar River Valley (Germany)--Economic conditions--Congresses.
Neckar River Valley (Germany)--History--Congresses.
Rhine River Valley--Economic conditions--Congresses.
Rhine River Valley--History--Congresses.
Harvard subject headings:
Neckar River Valley (Germany)--Economic conditions--Congresses.
Neckar River Valley (Germany)--History--Congresses.
Rhine River Valley--Economic conditions--Congresses.
Rhine River Valley--History--Congresses.
Princeton subject headings:
Neckar River Valley (Germany)--Economic conditions--Congresses.
Neckar River Valley (Germany)--History--Congresses.
Rhine River Valley--Economic conditions--Congresses.
Rhine River Valley--History--Congresses.