Columbia subject headings:
Europe, Eastern--Population--Congresses.
Migration, Internal--Europe, Eastern--Congresses.
Urbanization--Europe, Eastern--Congresses.
Harvard subject headings:
Europe, Eastern--Population--Congresses.
Migration, Internal--Europe, Eastern--Congresses.
Urbanization--Europe, Eastern--Congresses.
Princeton subject headings:
Europe, Eastern--Population--Congresses.
Migration, Internal--Europe, Eastern--Congresses.
Urbanization--Europe, Eastern--Congresses.