https://www.opendemocracy.net/democraciaabierta/bernardo-guti-rrez/madrid-un-laboratorio-democr-tico
https://www.crisisgroup.org/latin-america-caribbean/andes/venezuela/seeking-best-skewed-poll-hard-choices-venezuela
https://fpc.org.uk/resisting-the-abuse-of-political-power/?mc_cid=735f127870&mc_eid=b36196fd97
http://ftp.iza.org/dp9466.pdf