https://publications.parliament.uk/pa/cm200203/cmhansrd/vo021126/debtext/21126-17.htm
https://www.gov.uk/government/news/david-davis-teesport-speech-implementation-period-a-bridge-to-the-future-partnership-between-the-uk-eu
https://ec.europa.eu/commission/publications/position-paper-essential-principles-financial-settlement_en