J.M. Berger and Jonathon Morgan’s path-breaking study of Islamic States use of Twitter published by Brookings 

Abstract from Brookings:

“Although much ink has been spilled on ISIS’s activity on Twitter, very basic questions about the group’s social media strategy remain unanswered. In a new analysis paper, J.M. Berger and Jonathon Morgan answer fundamental questions about how many Twitter users support ISIS, who and where they are, and how they participate in its highly organized online activities.”