The webapp provides for each item the link on ECB's website.
Speeches for : Yves Mersch where "chain" appeared
2020-06-25 : The World Economy Transformed2019-09-02 : Money and private currencies: reflections on Libra
2019-05-29 : Back to stable
2019-01-11 : Tenth anniversary of the euro in Slovakia
2018-05-14 : Virtual currencies ante portas