Konrad, Kai A. Public Economics, MPI for Tax Law and Public Finance, Max Planck Society;
https://voxeu.org/article/citizenship-trade-inside-eu-sovereignty-rights-need-be-realigned (Verlagsversion)
Konrad, K. A., & Rees, R. (2020). Citizenship trade in the EU: Sovereignty rights need to be realigned. VoxEU.