http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025995#pone.0025995.s001http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0025995#pone.0025995.s001
http://arxiv.org/pdf/1107.5728v2.pdf
http://www.argenpress.info/2012/10/660-individuos-y-147-corporaciones.html
