Columbia subject headings:
Harvard subject headings:
Mineral industries--Austria--History--Congresses.
Mineral industries--Europe, Central--History--Congresses.
Mineral industries--Germany--History--Congresses.
Mineral industries--Norway--History--Congresses.
Social security--Austria--History--Congresses.
Social security--Europe, Central--History--Congresses.
Social security--Germany--History--Congresses.
Social security--Norway--History--Congresses.
Princeton subject headings:
Mineral industries--Austria--History--Congresses.
Mineral industries--Europe, Central--History--Congresses.
Mineral industries--Germany--History--Congresses.
Mineral industries--Norway--History--Congresses.
Social security--Austria--History--Congresses.
Social security--Europe, Central--History--Congresses.
Social security--Germany--History--Congresses.
Social security--Norway--History--Congresses.