Columbia subject headings:
Harvard subject headings:
Merchants--China--Tianjin--History.
Salt industry and trade--China--Tianjin.
Tianjin (China)--Commerce--History.
Tianjin (China)--Economic conditions.
Princeton subject headings:
Merchants--China--Tianjin--History.
Salt industry and trade--China--Tianjin.
Tianjin (China)--Commerce--History.
Tianjin (China)--Economic conditions.