https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1708en.pdf
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef22040en.pdf
https://www.esri.ie/sites/default/files/media/file-uploads/2020-01/Slides_1.pdf