Columbia subject headings:
Communism--History--Sources--Catalogs.
International Institute of Social History--Archives--Catalogs.
Social history--Sources--Catalogs.
Socialism--History--Sources--Catalogs.
Working class--History--Sources--Catalogs.
Harvard subject headings:
Europe--History--Sources--Bibliography--Catalogs.
Europe--Social conditions--Manuscripts--Catalogs.
International Institute of Social History--Archives--Catalogs.
Political parties--Europe--History--Manuscripts--Catalogs.
Working class--Europe--History--Manuscripts--Catalogs.
Princeton subject headings:
Europe--History--Sources--Bibliography--Catalogs.
Europe--Social conditions--Manuscripts--Catalogs.
International Institute of Social History--Archives--Catalogs.
Political parties--Europe--History--Manuscripts--Catalogs.
Working class--Europe--History--Manuscripts--Catalogs.