http://www.motherjones.com/politics/2015/06/right-wing-extremism-explainer-charleston-mass-shooting-terrorism
"Researchers at the US Department of Homeland Security, New America Foundation, Southern Poverty Law Center, University of Maryland, and the Combating Terrorism Center at West Point have all compiled data on right-wing extremist violence using varying criteria over different periods of time, most of them going back to the mid 1990s, when the Oklahoma City bombing riveted attention on the problem."
