Columbia subject headings:
Harvard subject headings:
China--History--Han dynasty, 202 B.C.-220 A.D
China--Social conditions.
Natural disasters--China
Princeton subject headings:
China--History--Han dynasty, 202 B.C.-220 A.D.
China--Social conditions--221 B.C.-960 A.D.
Natural disasters--China--History.
Natural disasters--Social aspect--China.