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https://www.hks.harvard.edu/sites/default/files/centers/mrcbg/working.papers/84_Harvard%20Working%20PaperTime%20for%20ClarityFinPAS.pdf
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https://www.brookings.edu/blog/up-front/2018/07/12/as-trump-twists-natos-arm-lets-run-the-math-on-defense-spending/?utm_campaign=Brookings%20Brief&utm_source=hs_email&utm_medium=email&utm_content=64421876
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https://reformscotland.com/wp-content/uploads/2018/04/The-VAT-opportunity.pdf