Science of a Tornado. (2013). The History Channel website. Retrieved 9:50, May 19, 2013, from http://www.history.com/videos/science-of-a-tornado.
Science of a Tornado. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/videos/science-of-a-tornado [Accessed 19 May 2013].
“Science of a Tornado.” 2013. The History Channel website. May 19 2013, 9:50 http://www.history.com/videos/science-of-a-tornado.
“Science of a Tornado,” The History Channel website, 2013, http://www.history.com/videos/science-of-a-tornado [accessed May 19, 2013].
“Science of a Tornado,” The History Channel website, http://www.history.com/videos/science-of-a-tornado (accessed May 19, 2013).
Science of a Tornado [Internet]. The History Channel website; 2013 [cited 2013 May 19] Available from: http://www.history.com/videos/science-of-a-tornado.
Science of a Tornado, http://www.history.com/videos/science-of-a-tornado (last visited May 19, 2013).
Science of a Tornado. The History Channel website. 2013. Available at: http://www.history.com/videos/science-of-a-tornado. Accessed May 19, 2013.