From the Serial Solutions Web Site:
In cooperation with the Conference of European National Librarians (CENL), the Summon Web-scale Discovery service from Serials Solutions will make the vast collections of The European Library and Europeana discoverable in the Summon unified index.
Summon users will be able to search across hundreds of millions of records from The European Library, an aggregation of collections from 48 European national libraries, as well as Europeana, a repository of digitized assets from across Europe. There are over 350 separate collections in The European Library including treasured materials dating as far back as the 8th century and millions of pages of full text content with resources in at least 35 languages. Europeana currently contains more than 23 million digital objects, from more than 1500 institutions across 33 countries.