https://www.esri.ie/system/files/publications/SUSTAT95_0.pdf
https://www.boeckler.de/pdf/p_imk_report_125e_2017.pdf
https://www.boeckler.de/pdf/p_study_hbs_376.pdf
https://www.esri.ie/sites/default/files/media/file-uploads/2020-01/Slides_1.pdf