https://www.nber.org/system/files/working_papers/w32002/w32002.pdf
http://www.cesifo-group.de/ifoHome/publications/working-papers/CESifoWP/CESifoWPdetails?wp_num=6433&CESifoWP.search=+
http://ecipe.org//app/uploads/2018/02/ECIPE_Occasional0218_HLM_V7.pdf
https://www.crisisgroup.org/es/latin-america-caribbean/mexico/mexico-votes-what-next-crime-and-us-ties