Columbia subject headings:
Harvard subject headings:
Emissions trading--Europe--Congresses.
Emissions trading--Germany--Congresses.
Environmental impact charges--Europe--Congresses.
Environmental impact charges--Germany--Congresses.
Environmental policy--Europe--Congresses
Environmental policy--Germany--Congresses
Environmental protection--Europe--Congresses
Environmental protection--Germany--Congresses.
Princeton subject headings:
Emissions trading--Europe--Congresses.
Emissions trading--Germany--Congresses.
Environmental impact charges--Europe--Congresses.
Environmental impact charges--Germany--Congresses.
Environmental policy--Europe--Congresses.
Environmental policy--Germany--Congresses.
Environmental protection--Europe--Congresses.
Environmental protection--Germany--Congresses.