A number should have a source.
Every numeric lookup result points to the bibliographic record it came from. Compare that record with the book in your hand.
Public catalogue sources
- Library of Congress SRU: MARC 082 classification fields.
- Open Library: edition metadata and work search.
- HathiTrust Bibliographic API: contributor catalogue records and their MARC fields.
- Harvard Library: classifications explicitly identified as DDC.
- K10plus SRU: catalogue search and MARC records.
ISBN lookup asks these sources without assigning one institution’s number as the winner. Title, author and topic search currently uses LC and Open Library to find candidates. A source listed here can still be temporarily unavailable for an individual request.
What our labels mean
From catalog record means the number is present in the linked record. ISBN associated means that record lists a valid matching ISBN. A work-level search result can combine editions; its numbers are not presented as an exact edition’s classification. Invalid or cancelled ISBN fields are excluded from direct matching.
Rule-derived numbers and model suggestions are separate result types. They are not enabled in this initial release. We do not fill gaps by guessing a number or presenting our small research model as a full Dewey classifier.
Coverage, differences and errors
Records can be incomplete or mistaken. The same ISBN can appear in different records, and numbers may differ in depth or meaning. We preserve these differences rather than claim a universal correct shelf mark. A missing number, an unconfirmed ISBN and a failed catalogue request are distinct outcomes.
Metadata attribution
Harvard Library makes bibliographic metadata available under CC0 and requests attribution to Harvard Library, OCLC and the Library of Congress where applicable, and observance of its community norms. We acknowledge these contributors. HathiTrust metadata can be subject to contributing institutions’ conditions. Source access is not a blanket licence to republish entire databases.
Independence
Dewey and Dewey Decimal Classification are registered trademarks of OCLC. This site is not affiliated with or endorsed by OCLC or the libraries named above. We do not copy or scrape paid WebDewey content. The ten-class explanations and chart are independently written learning material.
Correcting a record
Open the linked source first to check its edition and original fields. A correction at a catalogue source may take time to appear here because responses can be cached for up to an hour. See contact details for reporting a problem with this site.