请帮我找下面这篇 paper，谢谢 ^.^
Bohorquez, J. C., Gourley, S., Dixon, A. R., Spagat, M., and Johnson, N. F.  (2009). Common ecology quantifies human insurgency. Nature, 462(7275):911-914.

网址：http://www.nature.com/nature/journal/v462/n7275/abs/nature08631.html