The webapp provides for each item the link on ECB's website.
Speeches for : Otmar Issing where "sovereign" appeared
2006-03-24 : The euro - a currency without a state2005-06-16 : European integration - achievements and challenges
2001-02-23 : Economic and Monetary Union in Europe: political priority versus economic integration?
2000-02-08 : European integration at the beginning of the new millennium
1999-09-20 : Europe: common money - political union?
1999-01-28 : The euro - four weeks after the start