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CrossRef, DOIs and E-books
By Amy Brand, PhD, Director of Business Development, CrossRef/PILA, Lynnfield, MA, USA

CrossRef, a publisher-run organization, allows scholarly and professional publishers to work together to improve the online research experience. In the six years since CrossRef launched its citation-linking network, it has grown well beyond the STM journal sphere to encompass various content types from highly diverse content producers.

Though book publishers have been slower to adopt the DOI than journal publishers, among the 22 million or so content items registered in CrossRef are more than 500,000 digital object identifiers (DOIs) assigned to monographs, major reference works, edited volumes and chapters within these works.

How CrossRef and DOIs Basically Work

The DOI, a NISO standard, is a unique alphanumeric label for digital content. The DOI is paired with an object’s URL in a central updatable directory and is intended to be published in place of the URL to prevent broken links if and when the content moves. CrossRef is the only DOI registration agency maintaining a DOI look-up system that renders our DOIs discoverable for linking on an automated basis by other participating publishers, libraries, researchers and vendors. CrossRef is also the only agency whose DOIs integrate with the OpenURL for appropriate linking.

CrossRef strives to be as inclusive as possible in terms of academic publishers eligible for membership and types of content supported. CrossRef’s annual membership fee is tiered based on publishing revenue, so content producers are asked to pay only what they can afford. There are also small per-DOI fees for deposit of archival content and more granular content, such as book chapters. On the technical side, CrossRef’s XML deposit schema has been expanded over the years to support metadata for a wide range of content types, including conference proceedings, standards, dissertations, working papers, technical reports, scientific databases, components and of course e-books.

How CrossRef Works in Terms of E-books

Publishers who have registered books with CrossRef thus far include Elsevier, Humana Press, Oxford University Press, Springer-Verlag, Taylor & Francis, the American Psychological Association, Wiley and a handful of others. Because e-book platforms are still PDF-based for the most part, CrossRef does not require that references in registered books link out they way do in journal articles. But all the functionality CrossRef now offers can apply equally well to books.

CrossRef’s newer services include several benefiting researchers accessing online content and benefiting e-book publishers. Following are a few details.

• Stored Query Alerts inform querying parties via email when DOIs searched for but not found eventually get registered.
• Web Deposit, for manual deposit of DOIs and metadata, makes it easier for publishers without an XML workflow to register their content.
• Free-Text Query provides a simple alternative to XML query via a cut-and-paste form that accepts text-based references and returns DOIs for matched citations.
• Multiple Resolution presents a user clicking on a DOI with a menu of publisher-supplied options, such as alternative sites and different formats for a publication. Multiple Resolution (MR) also allows the user to view related resources, drill up or down within a publication, access associated metadata, get more information about the author, and purchase or acquire rights to the content.

E-book applications for MR are especially compelling. Publishers can use MR to offer links to related titles, author information and online purchasing options for books. For example, publishers working with secondary e-book platforms can through MR offer links to content on these services. Though this may appear to be redundant with local link resolvers, in fact, OpenURL link servers can use the publisher-controlled links to augment their existing knowledgebases for display to library users. At the same time, MR enables more robust linking options for users without OpenURL-compliant link resolvers, a group still in the majority.

CrossRef and Publishers Continue to Work Together

To serve the research community directly, CrossRef maintains a freely available OpenURL resolver allowing users to enter an OpenURL and be directed to registered content. We have also recently opened to the public our free-text query service to allow scholars to use the tool in an editorial capacity, to check references and to pull DOIs into manuscripts prepublication. These are just a few of the many ways in which publishers working together through CrossRef help the global research community.

We at CrossRef expect to see e-book registration and linking grow significantly in the next several years. Making citations to the full range of scholarly content types linkable clearly improves the user experience.

 www.crossref.org