@jackcosgrove: Source? As I understand, the closest prior art to PageRank was HITS (as I called out earlier).

I'm sorry, I was mistaken. It was Web of Science, not PubMed.

Garfield, Garfield, Eugene. Citation indexing: Its theory and application in science, technology, and humanities. New York: Wiley, 1979, P. 1.

http://garfield.library.upenn.edu/ci/chapter1.PDF

During my investigation I found this article which claims an even earlier origin for this algorithm: https://m.phys.org/news/2010-02-google-pagerank-like-algorit...

These aren’t algorithms, they are just hand waving intuition that is “on the right track” but not quite there. You see similar “prior art” to Newtonian physics, for example, but there is still a huge leap from “oh, there might be something in these linkages” to “if we compute the stationary distribution of the Markov chain over the graph, we know the relative importance of each node.” Kleinberg was the first to algorithmically and rigorously codify this intuition.

PubMed was using a PageRank type algorithm before Google.