Columbia subject headings:
Harvard subject headings:
Ainu--History--Congresses.
Hokkaido (Japan)--Commerce--History--Congresses.
Subcontracting--Japan--Hokkaido--Congresses.
Princeton subject headings:
Ainu--History--Congresses.
Hokkaido (Japan)--Commerce--History--Congresses.
Subcontracting--Japan--Hokkaido--Congresses.