https://theconversation.com/radicalizacion-violenta-similitudes-y-diferencias-en-la-evolucion-del-ira-y-eta-196509
https://blogs.lse.ac.uk/europpblog/2021/10/22/de-facto-differentiation-in-action-why-poland-will-stay-in-the-eu-with-or-without-the-blessing-of-brussels/
http://library.fes.de/pdf-files/bueros/suedafrika/02828.pdf