Self Propelled vs. Towed Artillery. (2013). The History Channel website. Retrieved 4:21, May 20, 2013, from http://www.history.com/videos/self-propelled-vs-towed-artillery.
Self Propelled vs. Towed Artillery. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/videos/self-propelled-vs-towed-artillery [Accessed 20 May 2013].
“Self Propelled vs. Towed Artillery.” 2013. The History Channel website. May 20 2013, 4:21 http://www.history.com/videos/self-propelled-vs-towed-artillery.
“Self Propelled vs. Towed Artillery,” The History Channel website, 2013, http://www.history.com/videos/self-propelled-vs-towed-artillery [accessed May 20, 2013].
“Self Propelled vs. Towed Artillery,” The History Channel website, http://www.history.com/videos/self-propelled-vs-towed-artillery (accessed May 20, 2013).
Self Propelled vs. Towed Artillery [Internet]. The History Channel website; 2013 [cited 2013 May 20] Available from: http://www.history.com/videos/self-propelled-vs-towed-artillery.
Self Propelled vs. Towed Artillery, http://www.history.com/videos/self-propelled-vs-towed-artillery (last visited May 20, 2013).
Self Propelled vs. Towed Artillery. The History Channel website. 2013. Available at: http://www.history.com/videos/self-propelled-vs-towed-artillery. Accessed May 20, 2013.