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Central Discovery Index &
Knowledge Base

Extensive and
reliable coverage
of research

Summon leverages a unified indexthe Ex Libris Central Discovery Index (CDI) and a knowledge base which reflects commercial, library-specific, and Open Access content. The coverage is deep and broad, reflecting available content from an extensive network of providers across a variety of resource types. This content is carefully aggregated and enriched to ensure its discoverability, regardless of provider.

Deep and broad coverage

Ex Libris tracks and works with the broadest range of resources in the industry, thanks to our close relationships with global and local content providers. This comprehensive approach provides users with the ability to successfully discover hard-to-find content across all sources.


Stewardship of metadata

The dedicated team of professional Ex Libris librarians uses its deep expertise in metadata management to continuously aggregate, enrich, and update resources. Our experts and content handling processes bring together and maintain data from all available sources, treating sources equally, to improve the discoverability and accessibility of content.



Authoritative and rich metadata

Records searched through Summon are optimized for discovery and contain extensive metadata. The level of record detail includes subject terms, controlled vocabularies, author-provided keywords, metadata from A&I sources, CrossRef DOIs, Ulrich’s peer-reviewed indicators, and more.


Community engagement

Customers play a critical role in suggesting additions to the CDI and 360 Knowledgebase. The Ex Libris Idea Exchange Content forum provides you with opportunities to submit, review and vote on ideas to help us grow our collections to meet both library and user needs.