Columbia subject headings:
Harvard subject headings:
Coal trade--China--Yu Xian (Shanxi Sheng)--History--20th century.
Yu Xian mei tan yun xiao gong si--History--20th century.
Princeton subject headings:
Coal trade--China--Yu Xian (Shanxi Sheng)--History--20th century.
Yu Xian mei tan yun xiao gong si--History--20th century.