Columbia subject headings:
Harvard subject headings:
Hydraulic engineering--China--Yi Xian (Hebei Sheng)--History.
Irrigation--China--Yi Xian (Hebei Sheng)--History.
Water resources development--China--Yi Xian (Hebei Sheng)--History.
Yi Xian (Hebei Sheng, China)--History.
Princeton subject headings:
Hydraulic engineering--China--Yi Xian (Hebei Sheng)--History.
Irrigation--China--Yi Xian (Hebei Sheng)--History.
Water resources development--China--Yi Xian (Hebei Sheng)--History.