Fiona B. Adamson. “Crossing Borders: International Migration and National Security,” International Security, Vol. 31, No. 1, Summer 2006,...
Justin Huggler. “EU police chief warns that 5,000 jihadists returned from Middle East – and new attack is likely,” The Telegraph, 2016, http://news.nationalpost.com/news/world/eu-police-chief-warns-that-5000-jihadists-returned-from-training-in-middle-east-and-new-attack-is-likely