Columbia subject headings:
Anthrax--United States--Prevention.
Letter mail handling--United States--Safety measures.
Postal service--United States--Safety measures.
United States Postal Service--Officials and employees--Health and hygiene.
United States Postal Service.
Harvard subject headings:
Anthrax--United States--Prevention.
Letter mail handling--United States--Safety measures.
Postal service--United States--Safety measures.
United States Postal Service--Officials and employees--Health and hygiene.
United States Postal Service.
Princeton subject headings:
Anthrax--United States--Prevention.
Letter mail handling--United States--Safety measures.
Postal service--United States--Safety measures.
United States Postal Service--Officials and employees--Health and hygiene.
United States Postal Service.