Roman, J.K., Chalfin, A.J., and Knight, C.R. (2009). Reassessing the cost of the death penalty using quasi-experimental methods: Evidence from Maryland. American Law and Economics Review, 11(2), 530-574.
Rubin, D.B. (1986). Statistics and causal inference: Comment: Which ifs have causal answers. Journal of the American Statistical Association, 81(396), 961-962.
Shepherd, J.M. (2005). Deterrence versus brutalization: Capital punishment’s differing impacts among states. Michigan Law Review, 104(2), 203-255.
Snell, T.L. (2010). Capital Punishment, 2009—Statistical Tables. Report, U.S. Department of Justice (NCJ 231676). Available: http://www.ojp.usdoj.gov/index.cfm?ty=pbdetail&iid=2215. [December 2010].
Zimmerman, P.R. (2004). State executions, deterrence, and the incidence of murder. Journal of Applied Economics, 7(1), 163-193.