Columbia subject headings:
Criminals--United States--Identification.
Firearms--Law and legislation--United States.
Firearms--Purchasing--United States.
Gun control--United States.
Information storage and retrieval systems.
Harvard subject headings:
Criminal records--United States.
Criminals--United States--Identification.
Firearms--Purchasing--United States.
Gun control--United States
Information storage and retrieval systems--Law enforcement--United States.
Princeton subject headings:
Criminal records--United States.
Criminals--United States--Identification.
Firearms--Purchasing--United States.
Gun control--United States.
Information storage and retrieval systems--Law enforcement--United States.