Columbia subject headings:
Harvard subject headings:
Darmstadt (Germany)--Economic policy.
Local transit--Germany--History.
Mainz (Rhineland-Palatinate, Germany)--Economic policy.
Mannheim (Germany)--Economic policy.
Municipal services--Germany--History.
Public utilities--Germany--History.
Princeton subject headings:
Energy policy--Germany--Darmstadt.
Energy policy--Germany--Mainz.
Energy policy--Germany--Mannheim.
Energy policy--Germany.
Local transit--Darmstadt.
Local transit--Germany.
Local transit--Mainz.
Local transit--Mannheim.