
https://www.bertelsmann-stiftung.de/fileadmin/files/BSt/Publikationen/GrauePublikationen/20200325_PEPP_GrundII.pdf

https://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.36.4.103

https://blogs.lse.ac.uk/brexit/2019/12/03/a-missed-opportunity-revisiting-the-euro-referendum-that-never-was-from-a-historical-perspective/