https://www.boeckler.de/pdf/v_2018_04_26_27_arg_co_determ.pdf
https://opportunityinsights.org/wp-content/uploads/2020/05/tracker_paper.pdf
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef18001en.pdf
https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1747en.pdf