https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1663en.pdf
https://www.esri.ie/system/files/publications/RS123.pdf
http://www.bsa.natcen.ac.uk/latest-report/british-social-attitudes-34/key-findings/context.aspx?_ga=2.25464057.552181158.1498632950-1412959047.1496247036
https://www.boeckler.de/data/downloads/IMK/FMM%20Konferenz%202023/v_2023_10_20_goekten.pdf