
https://ec.europa.eu/research/evaluations/pdf/archive/other_reports_studies_and_documents/hlg_2017_report.pdf

https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef18032en.pdf

https://www.instituteforgovernment.org.uk/sites/default/files/publications/5890%20IFG%20-%20Whitehall%20Monitor%202018%20web.pdf