Columbia subject headings:
National security--Europe, Eastern--Congresses.
National security--Germany--Congresses.
National security--International cooperation--Congresses.
National security--Poland--Congresses.
Harvard subject headings:
Germany--Foreign relations--Poland--Congresses.
National security--Europe--Congresses
National security--Germany--Congresses.
National security--Poland--Congresses.
Poland--Foreign relations--Germany--Congresses.
Princeton subject headings: