What Library Guides Link: 71 Tools in 35,640 Links<br>Skip to the tool Library Research Guides Catalogue Sources: 71 Calculation Tools in 35,640 Outbound Links<br>35,640 outbound links from 2,193 university research guides. 71 pointed to a calculation tool.
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A survey conducted on 18 August 2026 across 368 English-language university library<br>installations on the LibGuides platform extracted 35,640 outbound links from 2,193 research<br>guides covering calculation-heavy subjects. Of those links, 71 pointed to a calculator,<br>converter, or spreadsheet tool. Five of the 71 were dead, and all five were assignment planners<br>rather than calculators. The result places a concrete number on an assumption that circulates<br>without evidence: that academic library guides are a productive place to find where<br>computational tools are cited and recommended.
What the survey set out to measure
Library research guides occupy a specific position in the web graph. They are maintained by<br>subject specialists, updated on institutional schedules, and linked from university domains<br>that carry substantial authority. They are frequently proposed as a discovery surface for<br>tools, on the reasoning that a subject librarian curating a page on structural engineering or<br>clinical nutrition would naturally include the calculators practitioners use.
The survey tested that reasoning directly. Two questions were posed. First, at what rate do<br>these guides link to calculation tools as opposed to information sources. Second, among the<br>links they do carry, what proportion have decayed, and what kind of resource fails most often.
Seven subject areas were selected because each has an established body of routine computation:<br>statistics, construction, HVAC, finance, logistics, nutrition, and electrical work. A guide<br>entered the sample if its title or subject classification placed it in one of those areas.
The funnel<br>StageCount Institutions in the public LibGuides directory469 English-language institutions analysed368 Guides enumerated via sitemap.xml50,034 Guides in the seven calculation subject areas2,193 Outbound links extracted from those guides35,640 Unique URLs after deduplication10,747 Distinct domains3,600 Domains with no DNS record67 Links whose anchor text or URL indicates a tool71 Tool links returning a dead status5
The compression between rows carries most of the information. The 35,640 raw links collapse to<br>10,747 unique URLs, a deduplication ratio of 3.3 to 1, which means the average distinct<br>resource appears in slightly more than three places. Those 10,747 URLs resolve to 3,600<br>domains, so the average domain is cited three times across the corpus.
The final row is the finding. Tool links constitute 0.199 percent of extracted links,<br>approximately two in every thousand. Distributed across 2,193 guides, that is one tool link for<br>every 31 guides in subjects defined by their computational content.
Method
Guides were enumerated from each installation's sitemap.xml. No search engine was<br>used at any stage. This choice was deliberate and it shapes what the numbers mean: search<br>indexes reflect crawl priority and popularity, while a sitemap reflects what the institution<br>itself publishes. Enumeration by sitemap produces a census of a platform rather than a sample<br>of what ranks well.
Links were extracted from guide bodies, with navigation chrome and platform boilerplate<br>excluded. Classification as a tool link required the anchor text or the URL path to contain a<br>tool indicator: calculator, converter, spreadsheet, and their common variants. This is a<br>lexical test and it is conservative in one direction and permissive in another, a point taken<br>up under limitations.
Status testing used HEAD requests, falling back to GET where the server returned a<br>method-not-allowed response or otherwise failed to implement HEAD. Only 404 and 410 were<br>counted as death. Status codes 403, 406, and 429 were treated as robot blocking and excluded<br>from the dead count, since they describe the crawler's reception rather than the resource's<br>existence.
Every candidate failure was then rechecked with a browser user-agent string. That second pass<br>discarded 24 false positives. The clearest illustration is app.dimensions.ai,<br>which returns 404 to an automated client and 202 to a browser. Without the recheck, the<br>reported decay rate would have been inflated by roughly a third of its candidate volume.
Separately, 67 domains had no DNS record at all. These are unambiguous failures and require no<br>HTTP negotiation to confirm.
Finding one: the corpus catalogues sources
The dominant content of these guides is bibliographic. Outbound links resolve overwhelmingly to<br>databases, journal platforms, publisher sites, government statistical agencies, standards<br>bodies, and professional associations. A guide on HVAC points to ASHRAE and to engineering<br>databases. A guide on nutrition points to federal dietary data and to indexed literature. The<br>librarian's function in these pages is to...