Columbia subject headings:
Harvard subject headings:
European Union--Europe, Central--Congresses.
Germany--Relations--Poland--Congresses.
Poland--Relations--Germany--Congresses
Sustainable development--Europe, Central--Congresses.
Princeton subject headings:
European Union--Europe, Central--Congresses.
Germany--Relations--Poland--Congresses.
Poland--Relations--Germany--Congresses.
Sustainable development--Europe, Central--Congresses.