Columbia subject headings:
Harvard subject headings:
Contract labor--China--Hebei Sheng--History.
Kai Luan mei kuang--History.
Wages--Coal miners--China--Hebei Sheng--History.
Princeton subject headings:
Contract system (Labor)--China--Hebei Sheng--History.
Kai luan kuang wu zong ju.
Wages--Coal-miners--China--Hebei Sheng--History.