American U-2 spy plane shot down. (2013). The History Channel website. Retrieved 4:41, May 23, 2013, from http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down.
American U-2 spy plane shot down. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down [Accessed 23 May 2013].
“American U-2 spy plane shot down.” 2013. The History Channel website. May 23 2013, 4:41 http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down.
“American U-2 spy plane shot down,” The History Channel website, 2013, http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down [accessed May 23, 2013].
“American U-2 spy plane shot down,” The History Channel website, http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down (accessed May 23, 2013).
American U-2 spy plane shot down [Internet]. The History Channel website; 2013 [cited 2013 May 23] Available from: http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down.
American U-2 spy plane shot down, http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down (last visited May 23, 2013).
American U-2 spy plane shot down. The History Channel website. 2013. Available at: http://www.history.com/this-day-in-history/american-u-2-spy-plane-shot-down. Accessed May 23, 2013.