Columbia subject headings:
Arbusow, Leonid, 1882-1951--Congresses.
Livonia--Historiography--Congresses.
Harvard subject headings:
Arbusow, Leonid, 1882-1951--Congresses.
Livonia--Historiography--Congresses.
Princeton subject headings:
Arbusow, Leonid, 1882-1951--Congresses.
Livonia--Historiography--Congresses.