Citations to Web pages in scientific articles: the permanence of archived references

We validate the use of archiving Internet references by comparing the accessibility of published uniform resource locators (URLs) with corresponding archived URLs over time.

We scanned the "Articles in Press" section in Annals of Emergency Medicine from March 2009 through June 2010 for Internet references in research articles. If an Internet reference produced the authors' expected content, the Web page was archived with WebCite (http://www.webcitation.org). Because the archived Web page does not change, we compared it with the original URL to determine whether the original Web page had changed. We attempted to access each original URL and archived Web site URL at 3-month intervals from the time of online publication during an 18-month study period. Once a URL no longer existed or failed to contain the original authors' expected content, it was excluded from further study. The number of original URLs and archived URLs that remained accessible over time was totaled and compared.

A total of 121 articles were reviewed and 144 Internet references were found within 55 articles. Of the original URLs, 15% (21/144; 95% confidence interval [CI] 9% to 21%) were inaccessible at publication. During the 18-month observation period, there was no loss of archived URLs (apart from the 4% [5/123; 95% CI 2% to 9%] that could not be archived), whereas 35% (49/139) of the original URLs were lost (46% loss; 95% CI 33% to 61% by the Kaplan-Meier method; difference between curves P<.0001, log rank test).

Archiving a referenced Web page at publication can help preserve the authors' expected information.