Columbia subject headings:
Harvard subject headings:
Energy policy--Germany
Renewable energy sources--Germany--History.
Renewable energy sources--Technological innovations--Germany--History.
Solar energy--Germany--History.
Solar energy--Technological innovations--Germany--History.
Princeton subject headings:
Energy policy--Germany.
Renewable energy sources--Germany--History.
Renewable energy sources--Technological innovations--Germany--History.
Solar energy--Germany--History.
Solar energy--Technological innovations--Germany--History.