The webapp provides for each item the link on ECB's website.
Speeches for : Otmar Issing where "optimum" appeared
2006-03-24 : The euro - a currency without a state2006-02-24 : Europe's Hard Fix: The Euro Area
2005-06-16 : European integration - achievements and challenges
2004-10-22 : EU enlargement and monetary integration
2001-02-23 : Economic and Monetary Union in Europe: political priority versus economic integration?