https://ukandeu.ac.uk/wp-content/uploads/2020/05/UKICE-Post-Brexit-Gov-NI-Report.pdf
https://www.oecd-ilibrary.org/docserver/9789264293083-en.pdf?expires=1529901663&id=id&accname=guest&checksum=4A5E0B0C79A72EF7A887DDB0119B4594
https://cerre.eu/wp-content/uploads/2023/07/CERRE-Draft-Issue-Paper-DMA-Output-Indicators.pdf
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/638135/6.3703_DEXEU_Northern_Ireland_and_Ireland_INTERACTIVE.pdf