Columbia subject headings:
Employee screening--United States.
Hazardous substances--Transportation--Security measures--United States.
Terrorism--United States--Prevention.
Truck drivers--Licenses--United States.
Harvard subject headings:
Employee screening--United States
Hazardous substances--Transportation--Security measures--United States.
Terrorism--United States--Prevention
Truck drivers--Licenses--United States.
Princeton subject headings:
Employee screening--United States.
Hazardous substances--Transportation--Security measures--United States.
Terrorism--United States--Prevention.
Truck drivers--Licenses--United States.