Columbia subject headings:
Education, Elementary--Balkan Peninsula--Congresses.
Education, Elementary--Europe, Eastern--Congresses.
General education--Balkan Peninsula--Congresses.
General education--Europe, Eastern--Congresses.
Harvard subject headings:
Education, Elementary--Balkan Peninsula--Congresses.
Education, Elementary--Europe, Eastern--Congresses.
General education--Balkan Peninsula--Congresses.
General education--Europe, Eastern--Congresses.
Princeton subject headings:
Education, Elementary--Balkan Peninsula--Congresses.
Education, Elementary--Europe, Eastern--Congresses.
General education--Balkan Peninsula--Congresses.
General education--Europe, Eastern--Congresses.