The webapp provides for each item the link on ECB's website.
Speeches for : Willem F. Duisenberg where "doubt" appeared
2003-10-22 : Maastricht and the future of Europe2000-11-10 : The euro and the single monetary policy
2000-04-13 : Introductory statement with Q&A
1998-09-18 : Signing ceremony for the Headquarters Agreement