1. Balassa, B. (1962). The theory of economic integration. London: Geor Unwin Ltd. ISBN 978-1-136-64630-0.
2. European Commission. (1970). Report to the Council and the Commission on the realisation by stages of Economic and Monetary Union in the Community (Werner Report) (Supplement to Bulletin 11-1970).
3. European Commission. (1990). One market one money (European Economy, 44).
http://ec.europa.eu/economy_finance/publications/pages/publication_summary7520_en.htm
. 12 May 2019.
4. Haas, E. B. (1970). The study of regional integration reflections on the joy and anguish of pretheorizing. International Organization, 24(4), 607–646.
5. Issing, O. (1996). Wir müssen den Spielraum beschränken. Der Spiegel 3/1996, 85–87.