https://www.publications.parliament.uk/pa/ld201617/ldselect/ldeucom/78/78.pdf
http://s.kathimerini.gr/resources/article-files/symfwnia-aggliko-keimeno.pdf
https://theconversation.com/la-anomalia-empirica-de-las-elecciones-en-argentina-donde-dos-mas-dos-no-suman-cuatro-217319