?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adissertation&rft.au=van+der+Spek%2C+S.M.&rft.aulast=van+der+Spek&rft.aufirst=S.M.&rft.degree=Bachelor&rft.date=2018&rft.title=The+relationship+between+migration+flows+and+ageing+populations+across+Europe