Best practice for book content

Scholarly and professional publishers are increasingly publishing book content online and depositing the metadata and identifiers with Crossref. Crossref has a critical mass of nearly 13 million book titles and chapters in its system of which 1.25 million are book titles. This means that there are nearly 1.25 million titles available for reference linking and other Crossref services like CrossMark and Similarity Check. However, reference linking from and between books is more limited than with journals because many books and book chapters are in PDF so the references are extracted, deposited with Crossref and linked.

The Crossref Books Advisory Group reviewed the original Crossref Best Practices for Books published in 2008 and has updated them. The goal of the best practices is to:

  • Maximize reference linking between books and other Crossref content types including journals and conference proceedings
  • Ensure that Crossref collects and distributes persistent identifiers and authoritative metadata for online books
  • Ensure that book content is part of all Crossref services
  • Enhance the discovery, visibility, and usage of book content

Registering metadata, linking, and Crossref DOI use

More detailed information about books is available on the Crossref website. Crossref members should:

  1. Register the content by depositing Crossref metadata at the time of online publication and assign Crossref DOIs at the title and chapter/entry level.
  2. Add outbound DOI links from references in books. Outbound links are DOIs written in the form of URLs, eg https://doi.org/10.1234/56789.  
  3. Deposit references from books with Crossref to enable Crossref Cited-by Linking.
  4. Instruct authors to cite specific chapters and entries using page numbers, chapter/entry titles and Crossref DOIs.
  5. Update editorial guidelines: Ask copyeditors to look for page numbers and chapter titles in book citations. Use Crossref tools to check references as part of the production process so that references can be corrected and missing information added.

Updates and versions

This section divides updates into two types: major versions and minor versions. Major content changes that may affect the interpretation of a work may mean a new edition with new ISBNs. Major version changes imply that the publisher will formally notify readers that content has changed (through errata, corrigenda, or new editions (which would also get a new ISBN).

Minor content changes are unlikely to affect a reader’s interpretation of the work, and the publisher will not generally draw attention to the changes with a new version. Just as publishers now decide when a new print edition or version is warranted, it is publishers’ responsibility to distinguish between major and minor versions in online content. Since a Crossref DOI is a citation identifier, a new DOI should only be issued if the new version will be cited differently. The same logic applies to differing formats, i.e. the file types or ’containers’ used to present content: a distinct DOI should not be registered for different formats unless the format will be cited in a different way. This means, for example, that you should not assign one DOI to an EPUB version of a book and another DOI to the PDF version of a book if the format doesn’t impact how the book is cited. Members may register a single DOI for all versions of a translated book. Distinct DOIs may also be registered for translated versions of content.

Given the above definitions the recommended best practice is:

  1. Assign new DOIs to new major versions or editions of books, chapters and entries. This practice will preserve the scholarly citation record. Older versions should remain available online with links to the latest version. In actual operation, a reader follows a link to the version cited and then has the option to link to the current version.
  2. Do not assign new DOIs to minor new versions of books, chapters and entries.
  3. Where book content is hosted on multiple platforms (e.g. NetLibrary, ebrary) and publishers can enable enable linking from a single DOI to those platforms they should use Crossref Multiple Resolution. This enables multiple URLs to be associated with one DOI.
  4. Publishers who need to assign distinct DOIs to single titles across multiple platforms may use Co-access.  Co-access allows multiple depositors to assign distinct DOIs to a single item. When enabled for participating publishers, the Crossref system will collate the distinct DOIs and direct them to a single landing page containing URLs to the resources on different platforms.

Citation matching

Book title queries

In order to enable citation matching at the title level, the minimum query MUST include the following elements:

  • book title
  • book author
  • book copyright year

In order to increase the accuracy of matching, publishers SHOULD ALSO include as many of the following elements as possible in the query:

  • editor (where appropriate)
  • ISBN
  • ISSN / DOI
  • publisher

Book chapters or reference entry queries

The metadata provided for a book title is used to identify book chapters during querying. This means that a book chapter query should include title metadata as well. The minimum query for a book chapter MUST include the following elements:

  • book title
  • title and subtitle should be separated with a colon (:)
  • book year
  • chapter author
  • first page

In order to increase the accuracy of matching, publishers SHOULD ALSO include as many of the following elements as possible in the query:

  • editor (where appropriate)
  • publisher
  • chapter title
    • Note, combining chapter title and chapter author return the best matches

DOIs in citations

Following a review in 2017 of common citation style guides and publishers’ instructions to authors, Crossref recommends the following guidelines for the use of DOIs in citations, of any style or format:

  • Including Crossref DOIs (Digital Object Identifiers) whenever they are available: https://search.crossref.org can be used to search for registered content
  • Expressing DOIs as links following Crossref DOI display guidelines
  • Describing in guidelines to authors use of these Identifiers for each content type  (aka formats, e.g. journals, conference proceedings, etc.), where journal citations are described separately from books(e.g.) and/or making a general statement about their broad applicability.
  • Books that have DOIs at the title and chapter levels should be cited accordingly.
  • Print materials, of any content type, may display Crossref Digital Identifiers, but should not have their own, print-only Crossref DOIs.
  • Providing information (to Crossref, if not publicly) on update cycles, when possible, and contact information for keeping in touch with questions or future developments (e.g. new content types).

Books on Multiple Platforms

Multiple Resolution and Co-access are options for addressing books distributed across multiple platforms. Multiple Resolution ties together all locations where content might be hosted under a single DOI and represents the most comprehensive solution to ensure that metadata and citations are maintained and provisioned together. In the event that those who host book content on behalf of other publishers cannot adopt the single DOI to content distributed across a number of different platforms, Co-access provides a last resort for these parties to independently assign DOIs and deposit metadata for such books.


Please contact our support team with any questions about registering or retrieving book metadata.

Last Updated: 2018 August 10 by Jennifer Kemp