European Commission : Directorate-General for Economic and Financial Affairs., Ilzkovitz, F., Dierx, A., Kovacs, V., & Sousa, N. (2007). Step towards a deeper economic integration: The internal market in the 21th century. A contribution to the single market review. Brussels- Belgium: European Comission: Directorate-General for Economic and Financial Affairs.

European Commission : Directorate-General for Economic and Financial Affairs., Fabienne Ilzkovitz, Adriaan Dierx, Viktoria Kovacs, and Nuno Sousa. Step Towards a Deeper Economic Integration: The Internal Market in the 21th Century. A Contribution to the Single Market Review. Brussels- Belgium: European Comission: Directorate-General for Economic and Financial Affairs, 2007.

European Commission : Directorate-General for Economic and Financial Affairs., et al. Step Towards a Deeper Economic Integration: The Internal Market in the 21th Century. A Contribution to the Single Market Review. Brussels- Belgium: European Comission: Directorate-General for Economic and Financial Affairs, 2007.