Columbia subject headings:
Educators--Poland--Biography--Congresses.
Jews--Poland--Biography--Congresses.
Korczak, Janusz, 1878-1942--Congresses.
Harvard subject headings:
Korczak, Janusz, 1878-1942--Congresses.
Princeton subject headings:
Korczak, Janusz, 1878-1942--Congresses.