https://www.ifri.org/sites/default/files/atoms/files/pe-3-2022_stark.pdf
https://sipri.org/sites/default/files/2017-09/yb17-summary-eng.pdf
https://www.crisisgroup.org/europe-central-asia/eastern-europe/ukraine/256-peace-ukraine-i-european-war
https://www.ifw-kiel.de/fileadmin/Dateiverwaltung/IfW-Publications/-ifw/Kiel_Working_Paper/2022/KWP_2218_Which_countries_help_Ukraine_and_how_/KWP_2218_Trebesch_et_al_Ukraine_Support_Tracker.pdf