Operation Barrel Roll begins. (2013). The History Channel website. Retrieved 5:32, May 25, 2013, from http://www.history.com/this-day-in-history/operation-barrel-roll-begins.
Operation Barrel Roll begins. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/this-day-in-history/operation-barrel-roll-begins [Accessed 25 May 2013].
“Operation Barrel Roll begins.” 2013. The History Channel website. May 25 2013, 5:32 http://www.history.com/this-day-in-history/operation-barrel-roll-begins.
“Operation Barrel Roll begins,” The History Channel website, 2013, http://www.history.com/this-day-in-history/operation-barrel-roll-begins [accessed May 25, 2013].
“Operation Barrel Roll begins,” The History Channel website, http://www.history.com/this-day-in-history/operation-barrel-roll-begins (accessed May 25, 2013).
Operation Barrel Roll begins [Internet]. The History Channel website; 2013 [cited 2013 May 25] Available from: http://www.history.com/this-day-in-history/operation-barrel-roll-begins.
Operation Barrel Roll begins, http://www.history.com/this-day-in-history/operation-barrel-roll-begins (last visited May 25, 2013).
Operation Barrel Roll begins. The History Channel website. 2013. Available at: http://www.history.com/this-day-in-history/operation-barrel-roll-begins. Accessed May 25, 2013.