https://www.jstor.org/stable/25472435
http://dip21.bundestag.de/dip21/btd/19/072/1907200.pdf
https://visual.ons.gov.uk/commonwealth-trade-in-focus-as-uk-prepares-for-brexit/
https://www.crisisgroup.org/europe-central-asia/eastern-europe/ukraine/260-peace-ukraine-ii-new-approach-disengagement