Columbia subject headings:
Harvard subject headings:
Labor unions--Japan--Okayama-ken--Political activity--History.
Okayama-ken Rōdō Kumiai Sōhyōgikai--History.
Socialism--Japan--Okayama-ken--History.
Princeton subject headings:
Labor unions--Japan--Okayama-ken--Political activity--History.
Okayama-ken Rōdō Kumiai Sōhyōgikai.