https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef18032en.pdf
https://theconversation.com/crisis-del-regimen-democratico-la-dominacion-de-los-partidos-politicos-en-espana-226276
https://www.opendemocracy.net/can-europe-make-it/ashoka-mody/german-social-democrats-have-alienated-their-base-and-fractured-europe?
https://www.access-info.org/article/29101