?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adissertation&rft.aufirst=Christian+W.&rft.aulast=Buiter&rft.au=Buiter%2C+Christian+W.&rft.date=2018&rft.degree=Bachelor&rft.title=Identifying+European+countries+that+are+most+vulnerable+to+population+ageing+problems