http://ec.europa.eu/social/BlobServlet?docId=5545&langId=en][56: European Commission (2015) Secondary earners and fiscal policies in Europe.
http://ec.europa.eu/social/BlobServlet?docId=5545&langId=en][56: Commission européenne (2015) Secondary earners and fiscal policies in Europe http://ec.europa.eu/justice/gender-equality/files/documents/150511_secondary_earners_en.pdf ]