• **Mathoverflow** has been studied as a "complex network" in <A HREF="https://www.researchgate.net/publication/283052716_Social_Achievement_and_Centrality_in_MathOverflow">Social achievement and centrality in MathOverflow</A>, by L.V. Montoya, A. Ma, and R.J. Mondragón.

• **MathSciNet** has been used by Jerrold W. Grossman to analyze the network of collaborations among mathematics in <A HREF="https://www.siam.org/pdf/news/485.pdf">Patterns of Collaboration in Mathematical Research:</A> *Apparently, the appropriate popular buzz phrase for mathematicians should be “eight degrees of separation”*.    
See also <A HREF="http://math.buffalo.edu/mad/stats/2005.research.patterns.pdf">Patterns of Research in Mathematics </A> by the same author.