Columbia subject headings:
Harvard subject headings:
Emigration and immigration--History--Congresses.
Emigration and immigration--Social aspects--Congresses
Immigrants--History--Congresses.
Princeton subject headings:
Case studies.
Emigration and immigration--Case studies.
Emigration and immigration--Congresses.
Migrations of nations--Congresses.
Missionaries--Case studies.
Missionaries--Congresses.
Refugees--Case studies.
Refugees--Congresses.