Engle, Pär Jason and Byron Shafer. "Where Are We in History? 2010 in the Longest Run" The Forum, 8.4 (2011): -. Retrieved 19 Jun. 2013, from doi:10.2202/1540-8884.1413

Engle, P. & Shafer, B. (2011). Where Are We in History? 2010 in the Longest Run. The Forum, 8(4), pp. -. Retrieved 19 Jun. 2013, from doi:10.2202/1540-8884.1413

Engle, Pär Jason and Byron Shafer. 2011. Where Are We in History? 2010 in the Longest Run. The Forum. 8(4): -. Retrieved 19 Jun. 2013, from doi:10.2202/1540-8884.1413