, , , , , ,

The prevalence of linkrot in scholarship has been documented in studies of journals in biology and medicine, communications, ecology, library and information science, and social science (Hennessey & Ge, 2013).  In a new cross-disciplinary study of linkrot in science, technology, and math abstracts and titles that are indexed in Thomson Reuter’s Web of Science (1996-2010), 31% of the uniform resource locators (URLs) were no longer live (Hennessey & Ge, 2013).  The study also investigated how effective two Internet archives were at mitigating the problem.  It found that 65% of the URLs had been archived in the Internet Archive’s Wayback Machine or in WebCite, a permanent linking and Internet archiving service for submitted URLs in medical journals.  To solve the linkrot problem, Hennessey and Ge propose manually or automatically submitting URLs that are still live to those archiving sites.

In another recent study of linkrot in citations contained in all U.S. Supreme Court decisions and in three law journals, Zittrain and Albert (2013) found a class of linkrot, called reference rot, at rates of 50% and approximately 70% respectively.  With reference rot, the URL cited is a working link but the content has changed and no longer supports the citation.  The study also discusses why the Internet Archive and WebCite are unreliable solutions to linkrot.  In a recent post on my blog, L.J. eds., I discuss a more effective solution being offered by a consortium of law libraries—perma.cc.

Permanently linking and preserving cited Internet sources

Perma.cc is a new webpage archiving tool developed by the Harvard Law School Library and the Harvard Innovation Lab.  The tool permanently links and redundantly stores user-submitted content that is cited in legal or scholarly works.  The idea is for authors to create the perma.cc links for URLs cited in their papers at the moment a citation is created (not after publication), preventing linkrot from the start.  A perma.cc link only becomes permanent when the journal that publishes the article vests it.  Details regarding how the tool works and who bears the risk of potential copyright violations are also discussed in my post.

How broadly will perma.cc be used?

Perma.cc is in the beta-testing phase and is not yet publically available.  While its current focus is on citations in legal scholarship, perma.cc could eventually be used more broadly.  However, it seems unlikely that a network of law libraries will support citations in scholarship across all disciplines.  Academic libraries providing platforms and other services for the publication of online journals and blogs could form similar consortia to provide a much-needed citation and archiving solution.


Hennessey, J., & Ge, S. X. (2013). A cross disciplinary study of link decay and the effectiveness of mitigation techniques. BMC Bioinformatics, 14(Suppl. 14, Proceedings of the Tenth Annual MCBIOS Conference): S5. doi: 10.1186/1471-2105-14-S14-S5. Retrieved from http://www.biomedcentral.com/1471-2105/14/S14/S5

Zittrain, J., & Albert, K. (2013, September 21). Perma: Scoping and addressing the problem of link and reference rot in legal citations [Working paper]. doi: http://dx.doi.org/10.2139/ssrn.2329161. Retrieved from the Social Science Research Network: http://ssrn.com/abstract=2329161