Columbia subject headings:
Herbicides--War use.
Operation Ranch Hand, 1962-1971.
Vietnam War, 1961-1975--Chemical warfare.
Harvard subject headings:
Herbicides--War use.
Operation Ranch Hand, 1962-1971.
Vietnam War, 1961-1975--Chemical warfare
Princeton subject headings:
Herbicides--War use.
Operation Ranch Hand, 1962-1971.
Vietnam War, 1961-1975--Chemical warfare.