1. Aisch, G., & Keller, J. (2015). What happens after calls for new gun restrictions? Sales go up. Retrieved 2 October 2019. https://www.nytimes.com/interactive/2015/12/10/us/gun-sales-terrorism-obama-restrictions.html.
2. Annear, S. (2014). Committee to reduce firearm violence calls for stricter state gun laws. Retrieved 12 December 2019. https://www.bostonmagazine.com/news/2014/02/03/committee-to-reduce-firearm-violence-report-massachusetts/.
3. Astor, M., & Russell, K. (2018). After parkland, a new surge in state gun control laws. Retrieved 2 October 2019. https://www.nytimes.com/interactive/2018/12/14/us/politics/gun-control-laws.html.
4. Bellisle, M. (2018). Gun background check system riddled with flaws. Retrieved 2 February 2020. https://www.pbs.org/newshour/nation/gun-background-check-system-riddled-with-flaws.
5. Bernal, J. L., Cummins, S., & Gasparrini, A. (2017). Interrupted time series regression for the evaluation of public health interventions: A tutorial. International Journal of Epidemiology, 46(1), 348–355. https://doi.org/10.1093/ije/dyw098.