https://www.socialeurope.eu/2017/06/trade-unions-and-the-decline-of-social-democracy/
https://blogs.lse.ac.uk/europpblog/2024/07/08/what-the-rise-of-chega-means-for-portuguese-democracy/
http://tdem.eu/
https://www.wilsoncenter.org/blog-post/helmut-kohl-collection-new-resource-post-cold-war-history