http://www.newscientist.com/article/dn7892-placebos-trigger-an-opioid-hit-in-the-brain.html#.VYHtqfntlBc
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067485
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067485
http://www.health.harvard.edu/blog/generic-drugs-dont-ask-just-tell-201301075766
http://www.health.harvard.edu/blog/generic-drugs-dont-ask-just-tell-201301075766
https://en.wikipedia.org/wiki/Placebo_in_history
https://en.wikipedia.org/wiki/Placebo
https://es.wikipedia.org/wiki/Sustancia_placebo
https://es.wikipedia.org/wiki/Efecto_placebo
https://es.wikipedia.org/wiki/Franz_Anton_Mesmer
https://en.wikipedia.org/wiki/File:Perkins_tractors_science_museum_2011.JPG#/media/File:Perkins_tractors_science_museum_2011.JPG
https://commons.wikimedia.org/wiki/File:Magnetismo_Animal.png#/media/File:Magnetismo_Animal.png
https://commons.wikimedia.org/wiki/File:A_practictioner_of_Mesmerism_using_Animal_Magnetism_Wellcome_V0011094.jpg#/media/File:A_practictioner_of_Mesmerism_using_Animal_Magnetism_Wellcome_V0011094.jpg
https://en.wikipedia.org/?title=Confirmation_bias#/media/File:MRI-Philips.JPG
https://commons.wikimedia.org/wiki/File:Injection_Syringe_01.jpg#/media/File:Injection_Syringe_01.jpg
https://en.wikipedia.org/wiki/File:Willendorf-Venus-1468.jpg#/media/File:Willendorf-Venus-1468.jpg