Columbia subject headings:
Harvard subject headings:
China--History--221 B.C.-960 A.D.
China--History--To 221 B.C.
China--History--To 221 B.C.--Errors, inventions, etc.
Princeton subject headings:
China--History--221 B.C.-960 A.D.
China--History--To 221 B.C.
China--History--To 221 B.C.--Errors, inventions, etc.