Extinction. (2013). The History Channel website. Retrieved 1:57, June 20, 2013, from http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear.
Extinction. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear [Accessed 20 Jun 2013].
“Extinction.” 2013. The History Channel website. Jun 20 2013, 1:57 http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear.
“Extinction,” The History Channel website, 2013, http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear [accessed Jun 20, 2013].
“Extinction,” The History Channel website, http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear (accessed Jun 20, 2013).
Extinction [Internet]. The History Channel website; 2013 [cited 2013 Jun 20] Available from: http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear.
Extinction, http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear (last visited Jun 20, 2013).
Extinction. The History Channel website. 2013. Available at: http://www.history.com/shows/life-after-people/videos/playlists/how-might-people-disappear. Accessed Jun 20, 2013.