http://www.ips-journal.eu/topics/european-union/article/show/say-it-with-feeling-2184/
https://www.brookings.edu/articles/want-ukraine-in-the-eu-youll-have-to-reform-the-eu-too/
http://www.elperiodico.com/es/politica/20171226/que-es-tabarnia-propuesta-secesion-barcelona-tarragona-resto-cataluna-6517873
https://www.eca.europa.eu/Lists/ECADocuments/SR21_08/SR_Frontex_EN.pdf