1. 18 U.S.C § 922(g).
2. ATF. Firearms BoAT FFL Type by state 07102017. In: ed. 2017.
3. 18 U.S.C § 922(s).
4. Law Center to Prevent Gun Violence. Universal background checks San Francisco, CA. 2017 http://smartgunlaws.org/gun-laws/policy-areas/background-checks/universal-background-checks/ (accessed 1 Aug 2017).
5. Law Center to Prevent Gun Violence. Licensing gun owners & purchasers policy summary San Francisco CA. 2013 http://smartgunlaws.org/licensing-of-gun-owners-purchasers-policy-summary/ (accessed 3 Dec 2013).