Citation linking in context: what others are doing

This is an extract from the paper Linking Electronic Journals: Lessons from the Open Journal Project written by the project development team and which appeared in D-Lib Magazine, December 1998

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Some other research projects are developing tools for citation linking. While the Open Journal project emphasised text recognition, matching, and linking, other projects are concerned with software agents that can find cited works on the Web (Han et al. 1997), and improved search services and parsing of other document formats (e.g., PostScript) to build automatic and comprehensive citation indexes (Giles et al. 1998). Another approach to serving  links separately from documents is Hyper-G, an electronic publishing package based on a Web server with an object-oriented distributed network database and a separate link database (Schmaranz 1996). Hyper-G has been used in journal projects with Springer-Verlag and Academic Press.

In one sense, serving links in this way is a rough-and-ready but practical method for implementing relationships, represented explicitly as links, between documents from different sources. This is a flexible approach but because no control is exercised over the documents, the links can be unstable and need to be rigorously mantained. At the other end of the spectrum, an ideal application-independent and stable way of identifying documents or their components might be the Digital Object Identifier (Davidson and Douglas 1998). Publishers to have prototyped applications represented in the the gallery of the International DOI Foundation include Academic Press, Elsevier, Springer-Verlag, and Wiley. The DOI is not yet an accepted standard, and to become so would require wide agreement. While links simply provide access to works, however, the DOI has a more demanding remit: "The intent of the (Association of American Publishers) AAP's Enabling Technologies Committee (which designed the DOI) was to support copyright protection, while ameliorating inconvenience to users, by supporting technology that promotes interoperability' (Rosenblatt 1997). It is not clear that these objectives can be easily reconciled without compromising user access. There are also concerns about possible limitations, such as restricting organizations that are permitted to assign DOIs to "legitimate"  publishers.

Between the DOI and link serving is Hellman's (1998) proposal for the Scholarly Link Specification Framework (SLinkS) which applies DOI-like identifiers to documents from different publishers but controlled via an intermediary service.

It is already clear from a number of publishing arrangements that the electronic scholarly literature will be dominated by cross-linking on citations between different journals and services. ISI Links has been announced as its means of mediating citation linking between Web of Science, collaborating publishers, and subscribing institutions. Linking applications where links are applied between different journals and documents directly managed by a single publisher have been described for the BioMedNet service (in Hitchcock et al. 1998b), HighWire Press  (Rubinstein 1997) and the Institute of Physics (Dixon 1998).

Some Web-based abstracts services enable third-party users to create links to entries in these sites. The best known is the National Library of Medicine's Medline service, the basis of widespread citation linking in biomedical fields. NCBI Citation Matcher allows users to find the Medline ID of any article in the database, given its bibliographic information, and to use that ID in a URL to retrieve the record. A related development, the PubMed project, additionally links back out from Medline entries to full-texts on the servers of cooperating publishers.

The Astrophysics Data System Abstract Service also helps with bibliographic code querying to link directly to abstracts from outside the abstract service.


Davidson, L. A. and Douglas, K. (1998) Digital Object Identifiers and Their Role in the Implementation of Electronic Publishing. Socioeconomic Dimensions of Electronic Publishing Workshop, held in cooperation with the 1998 IEEE International Conference on Advances in Digital Libraries, April 1998
or see the updated version version in html
Digital Object Identifiers: Promise and Problems for Scholarly Publishing. Journal of Electronic Publishing, Vol. 4, issue 2, December

Dixon, A. (1998) The Wannabee Culture: Why No-One Does What They Used to Do. Issues in Science and Technology Librarianship, Winter

Giles, C. L., Bollacker, K. D. and Lawrence, S. (1998) CiteSeer: An Automatic Citation Indexing System. Proceedings of the third  ACM International Conference on Digital Libraries, Pittsburgh, USA, June (ACM: New York)

Han, Y., Loke, S. W. and Sterling, L. (1997) Agents for Citation Finding on the World Wide Web. In PAAM 97: Proceedings of the Second International Conference on the Practical Applications of Intelligent Agents and Multi-Agent Technology (Practical Application Company: Blackpool, UK), pp. 303-317

Hellman, E. (1998) Scholarly Link Specification Framework (SLinkS), public draft #1.5, November 24

Hitchcock, S., Quek, F., Carr, L., Hall, W., Witbrock, A. and Tarr, I. (1998b) Towards Universal Linking for Electronic Journals. Serials Review, Vol. 24, No. 1, Spring, 21-33

Rosenblatt, B. (1997) The Digital Object Identifier: Solving The Dilemma Of Copyright Protection Online. The Journal of Electronic Publishing, Vol. 3, Issue 2, December

Rubinstein, E. (1997) Notice the Library Sprouting on Your Desktop? HMS Beagle, issue 15, September (registration required)

Schmaranz, K. (1996) Professional Electronic Publishing in Hyper-G: The Next Generation Publishing Solution on the Web. WebNet 96, San Francisco, CA

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