https://www.aicgs.org/publication/refugees-terrorism-and-a-failing-security-architecture/
http://www.ecfr.eu/article/commentary_germanys_defence_commitments_nothing_but_paper_tigers
http://www.ecfr.eu/page/-/Keeping_Europe_Safe_After_Brexit2.pdf
https://sipri.org/sites/default/files/2017-09/yb17-summary-eng.pdf
https://www.cesifo-group.de/DocDL/ifoDD_18-01_03-09_Ochsner.pdf
http://dip21.bundestag.de/dip21/btd/19/007/1900700.pdf
http://peaceandsecurityindex.org/wp-content/themes/peaceandsecurity/images/PSFG-report.pdf
https://www.un.org/disarmament/wmd/nuclear/npt/text
https://ec.europa.eu/commission/sites/beta-political/files/security_defence_and_foreign_policy.pdf
https://www.brookings.edu/research/a-post-american-europe-and-the-future-of-u-s-strategy/