CrossRef’s Joe Wass Writes:
This information is interesting because it shows not only where DOI hyperlinks are found across the web, but also when they are actually followed. This data allows us a glimpse into scholarly citation beyond references in traditional literature.
We have filtered out domains that belong to Crossref member publishers to highlight citations beyond traditional publications.
Here are numbers 10-7.
The complete Top 10 list, both charts, and links to some useful CrossRef tools are available here.
The post also includes a chart showing HTTP vs. HTTPs referral traffic during 2015 and early 2016.
By the way, it’s worth noting that the second most popular referring domain (see the list) has a scholarly/academic search site like Google Scholar and Microsoft Academic. You can see it here ||| translated version here (poor) ||| search results page here (better).