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Jihadi Julian Just'd
This report about the tribes of Raqqa, their history, economy, and relationships with the various factions of the Syrian conflict is one of the best pieces of scholarship on Syria I've ever read. Really good stuff, and it's a relatively short read. http://www.washingtoninstitute.org/uploads/Documents/pubs/PolicyNote39-Raqqa.pdf
i recall when he was assassinated no rebel group claimed responsibility. Which is very unusual especially considering he was such a high-value target.