
https://www.pymnts.com/news/b2b-payments/2020/deloitte-becomes-first-of-big-four-to-break-up-business/

https://www.oecd-ilibrary.org/docserver/cb6d9eca-en.pdf?expires=1654579866&id=id&accname=guest&checksum=058AA472061C4F1B77F0DDF5D1BCBA31

https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef22024en.pdf