Hmmm…
This definitely reveals different academic qualifications, but perhaps only reveals substructure for the humanities, i.e. fields where you need to read a lot of books, and authors matter.
On the side of physical sciences you see little structure. (you only need two electrodynamics books, introductory and advanced, and it’s irrelevant who wrote them)
Maps based on co-citations/paradigms I think look better there:
https://www.americanscientist.org/article/visualizing-disciplines-transforming-boundaries