Sources:

http://nationalinterest.org/feature/washington-watching-the-5-deadliest-terrorist-groups-the-11687

http://www.history.com/topics/9-11-attacks

https://m.youtube.com/watch?v=xsmc_rS2jOo

http://en.m.wikipedia.org/wiki/List_of_terrorist_incidents,_2014

http://listovative.com/top-10-most-dangerous-terrorist-organizations-in-the-world/

http://www.shmoop.com/war-on-terror/summary.html